Hello, and welcome to Sports Mole's live coverage of the Wimbledon quarter-final between Andy Murray and Vasek Pospisil.

We've reached that stage of Wimbledon where apart from Rafael Nadal, all of the big-hitters are vying to add another major title to their cabinet, but with the top four seeds still remaining in the draw, and a number of in-form players with little to lose, anything can happen in the final few days of this year's action at SW19.

Novak Djokovic, the defending champion, against Marin Cilic will take place on the main show-court at SW19 later this afternoon, but first up on Centre this afternoon is Andy Murray's clash with Vasek Pospisil. It was at this stage last year when the majority of British supporters were anticipating a fairytale defence for Murray, but Grigor Dimitrov showed on that afternoon that it's very rarely plain-sailing in the last eight. Vasek Pospisil is a huge underdog, but he will relish the chance to take on the world number three.

So then, how would we rate Andy Murray's current performance at this year's Wimbledon so far? Seven, maybe eight, out of 10? For the most part, the 28-year-old has been excellent but he has suffered lapses in concentration and form in three of his four matches. That said, he's also come through the adversity that was largely his own doing. Murray will be aware though that he still has improvements to make if he is to have a chance of winning his second Wimbledon title.

As for Vasek Pospisil, it's fair to say that he has been the surprise performer of the tournament. He's yet to face a player inside the world's top 20, but after seeing off Fabio Fognini in four sets, he overturned deficits against James Ward and Viktor Troicki to book his place in his first Grand Slam quarter-final.

STATS! As far as aces are concerned, Pospisil is the big winner with 79 in four matches, but he has also played a lot more tennis than Murray. That stat is cancelled out to some extent by Murray's impressive return game, with the Scot having broken serve on 20 occasions in his first four matches. Murray also possesses a break-point conversion rate of 51%, higher than any player who has broken more than 10 times.

HEAD TO HEAD! The two players have met on three occasions over the past year, with Murray winning each match without conceding a set. However, Pospisil has got himself into decent positions, especially in Rotterdam, without taking full advantage. He won't look back at his record against Murray with any degree of confidence, but if he can take any chances that come his way, who knows.

A win for Murray wouldn't see him catch Roger Federer in second place in the world rankings, but Pospisil would make huge strides up the standings if he can an upset. The Canadian would reach 21st place if he can reach the last four, a rise of 35 places from where he began the tournament.

The ballboys and line judges have just made their way onto Centre Court, where they have been joined by Prince William and the Duchess of Cambridge. David Beckham is here too. A special occasion for all concerned.

Here comes the two players to a standing ovation, who have been warned by the tournament referee that there is a bit of rain in the area. Hopefully that won't be an issue and the roof won't be needed.

The toss has been won by Vasek Pospisil, and he has elected to serve first. The Canadian needs to make a fast start to this match. You'd have thought, anyway.

Murray has spent eight hours and 50 minutes on court, playing 11 sets. Pospisil has played 11 hours and 32 minutes and played 19 sets, as well as playing several doubles matches. Will that be a factor? We will have to wait and see.

The warm-up is complete and we are ready to get started. How will Pospisil deal with his opening service game?

The Canadian begins with a one-two behind his fist serve, which is followed by a serve-and-volley. An outswinging serve forces Murray to go long to create three game points before he ends with a superb forehand winner into the corner. Excellent start for the underdog.

Murray eases into his opening service game by taking the opening two points, before Pospisil goes long with a return. The game is sealed when the Canadian goes long with a forehand.

BREAK! Murray reaches 15-30 after a volley and forehand winner, but on the next point, Pospisil makes his way to the net to force the mistake. Murray reaches break point with a stunning return that sets up the easy conversion into the open court, and the Scot strikes first when Pospisil can only put a difficult backhand volley into the net.

Like in first service game, Murray coasts into a 30-0 advantage before a first serve proves too hot to handle. Murray has three game points, but he misses a relatively easy forehand to keep Pospisil in the game. Arguably his worst second serve in his career takes the score to 40-30, but he eventually takes the game with a big serve down the middle.

That's your lot for now, I'm afraid. The rain that was predicted is coming down and the players have made their way off court.

I'd say that there is a fair chance of the roof being used over the next few minutes. The rain is coming down pretty hard. That said, if we are only due a 15-minute suspension, I imagine that the organisers and the players will be keen to continue the match without the roof.

According to the BBC, this heavy shower is scheduled to last no more than 10 minutes but more showers could be on their way over the next couple of hours. Sounds like it would make sense to use the roof, but the tournament referee is giving it some time before making his decision.

Sounds reasonable...

It has been announced that play should get back underway in around 20 minutes, providing that the rain clears. Looks like @WimbledonRoof is going to be disappointed.

Slowly but surely, the covers are being brought off. It's starting to look much brighter, but we shouldn't be surprised if we get another shower. This time last week, it was almost 35C. We are now getting frustrated with rain. British weather...

Everyone is making their back out onto Centre Court. We'll be back underway in just a few minutes. Murray earned the early break before the rain intervened.

Pospisil restarts the contest on the front foot but Murray reaches 30-15 with a heavily-sliced backhand. Pospisil earns two game points with a serve-and-smash but Murray remains in the game by drilling a forehand straight back at his opponent. However, Pospisil holds with a huge serve out wide.

Pospisil has looked rejuvenated since the break and a double fault and baseline mistake from Murray give him 0-30. Murray is lucky to avoid three break points when the Canadian sends a smash wide, before the world number 56 blasts a forehand return long. Two more efforts into the net from Pospisil hands Murray the game.

As you'd expect, Pospisil is winning the majority of the points behind his first serve and it's enough to earn him two game points. Another huge delivery forces Murray to go long.

Murray catches the line with a second serve and it forces the mistake out of Pospisil before a fierce backhand down the line earns the Scot 30-0. Two game points are created when a big first serve isn't handled by Pospisil, before the game comes to an end with an ace from Murray.

Aside from the game in which he was broken, Pospisil has began every service game superbly, and a love hold is sealed when Murray can't do anything with a second serve.

SET! Pospisil is holding his own when the two become embroiled in a lengthy exchange but the unforced errors are still being made and he gifts Murray 30-0. However, after halving the deficit, he looks on course for 30-30 before Murray stages a remarkable recovery which ends with a smash. Centre Court are on their feet. It's two set points, but the first is saved with a delightful backhand volley from Pospisil. This is warming up now! The second is saved too when Murray goes long, but he creates a third when Pospisil hits a return just wide. It's taken on this occasion when Pospisil nets, and Murray edges ahead on Centre Court.

Over on Court One, Roger Federer has taken the lead against Gilles Simon, winning the first set 6-3. You can follow that match by clicking here.

Since the restart, Pospisil has looked very secure on serve and that continues here. A love hold is sealed with an ace out wide and despite the one-set lead, Murray has something to think about.

After Murray takes the opening point, Pospisil levels things up with a terrific volley that sets up a routine conversion. Murray hits back with a strong forehand and well-directed backhand for two game points, but a second serve sits up, allowing Pospisil to drill a return into the corner. Murray takes the game, but he's a tad fortunate when Pospisil goes marginally wide with a makable passing shot.

For just the second time in the match, Murray has 0-15 on the Canadian's serve, but he replies with another sublime volley. The 25-year-old is playing some brilliant stuff and he races through the remainder of the game with more impressive net play behind his serve.

The opening two points are shared after both marginally miss with attacking shots, before Murray edges 30-15 ahead when Pospisil miscues a forehand. The game is sealed after two wayward returns from the world number 56.

Murray reaches 0-15 when Pospisil nets a volley off a return, and that soon becomes 0-30 when the Canadian sends a forehand wide. Two huge serves from Pospisil get him back to 30-30, before some sharp work at the net helps him earn a game point. A super one-two off serve sees him regain the lead, and although Murray missed out from 0-30, Pospisil won that game rather than Murray losing it.

It's Pospisil's chance to have a look at 15-30 after a Murray mistake, but the Scot gets back to 30-30 with a huge forehand that is sent long by his opponent. Murray's brings up game point with a smash into the open court before the hold is sealed when Pospisil hooks a return wide.

Pospisil's fourth ace of the match secures a 30-0 lead, but the deficit is halved when Murray catches the line with a slice. The Canadian throws in a double fault to gift Murray a look at 30-30, but Murray gifts a point back to his opponent with a poor forehand. The game is sealed with a drop shot to regain the lead, and judging by the clouds, we could be in for some rain.

Yep, here come the ground staff. Play has been suspended. Apparently, it should only last 10 or 15 minutes.

It will be interesting to see who the break favours. Pospisil had found a rhythm with his serve, but at the same time, Murray must return having to serve to get back on level terms in the set. We'll bring you an update on a possible resumption as soon as we have it.

Looks like the Wimbledon roof is getting its wish. It's being closed and we are scheduled to start at 3.20pm.

Over on Court One, Roger Federer had been serving for the second set but for the first time in over 100 games, he had his serve broken. However, the Swiss remains 6-3 6-5 up against Gilles Simon. You can follow that match by clicking here.

For the third and final time this afternoon, everyone makes their way back out onto Centre Court. With the sun now out, it's a bit comical that the roof has been closed, but that will be how it stays for the remainder of the match.

Who will benefit from the roof being closed? Who knows, but the ball is likely to go through the air and off the ground a little slower.

Right then, here we go. It will be Murray serving at 4-3 down in the second set, having earlier won the first set.

Murray restarts the match with a first serve that is sent into the net by his opponent, but the scores are level when Pospisil catches the line with a forehand. Murray opens up a 40-15 advantage before Pospisil concedes the game when sending a return long.

A super one-two behind his first serve gets Pospisil off to a positive start before he sneaks in to put away a volley for 30-0. Murray sends a return long to concede three game points, but he stays in the game with an excellent return. It's a momentary reprieve though as Pospisil connects with a venomous first serve.

Murray catches the line with two huge serves to earn three game points before a drive volley into the open court seals the game.

BREAK! Murray settles into a rally beautifully and he grinds down Pospisil for 0-15, but the Canadian levels things up with an ace, his fifth of the match. Some aggressive play at the net earns 30-15, but Murray finds great length from the back of the court to remain in with a shout at 30-30. It's break point to Murray after he wrong-foots Pospisil at the net, and it's taken with a glorious cross-court backhand.

At 30-30 during that game, Pospisil was given a time violation warning. At that stage of the game, it appeared harsh, but he averaged 30 seconds between points during that game. He needs to be at 20 seconds or below.

SET! Murray looks tuned in now, catching the line with a first serve before reaching 30-0 with a flat forehand into the corner. As I say that, he throws in a double fault. This game isn't over. He replies with a fantastic smash on the back foot to earn two set points, and the first is taken when a return is sent into the net.

Pospisil needs to begin this third set in positive fashion, but Murray reaches 15-15 with a quite ridiculous backhand winner at the net. Pospisil then double faults, before Murray chases down a volley to put away a winner. The Scot has two break points, but the Canadian saves both with first serves. A third takes him to game point, which is taken with a serve-and-volley. Big hold.

Murray looks in danger of falling 0-30 behind but a miraculous recovery and ace out wide gets him back on track at 30-15. A second ace earns two game points, but he only needs one when he deals with a fizzing return from his opponent.

Back-to-back aces take Pospisil to 30-0 but he misses an easy volley at the net to allow Murray to halve the deficit. The Canadian produces another double fault, and although he dominates the next exchange, he ends up finding the net. It's break point to Murray, but it's saved with a big first serve. Pospisil finds the ace to seal the hold, another huge one at that.

Murray breezes into a 30-0 lead, which soon becomes 40-0 when Pospisil clips the top of the net with a forehand. The Canadian remains in the game with a decisive return, but he can't repeat that effort on the next point.

A return winner from Murray is cancelled out by an ace from Pospisil, before Murray misses the chance to reach 15-30 with a cross-court backhand. Pospisil comes through with a hold to 15 and he's definitely still active in this match. Over on Court One, Federer has got the job done against Simon, winning in straight sets.

A backhand slice into the tramlines from Murray gives Pospisil the advantage, but it's handed straight back with a forehand into the net. A return goes just long for 30-15 before a first serve return is sent into the net. Two game points for Murray, but that is reduced to one when the Scot slices into the net. Pospisil concedes the game with a forehand error and we remain on serve in this third set.

After the opening two points are shared, Pospisil sends a weak backhand into the net. The pressure is building and a superb return from Murray secures two break points. The first is saved with a big serve out wide, as is the second after the Canadian constructs a wonderful point. He's hanging on in there. The game is saved when Murray twice goes long.

Murray powers to a love hold to keep the pressure on Pospisil, who is having to work hard to hold serve.

BREAK! Murray looks pumped for this return game and he reaches 0-30 after two shot-perfect rallies. Pospisil receives another time violation warning - resulting in a loss of first serve - but he halves the deficit with an aggressive point. A big first serve gets him back to 30-30, but Murray has break point after catching the line with a floated return. Despite a hot-dog shot from Pospisil, the break is sealed with a backhand winner from Murray and he will serve for the match.

MATCH! Pospisil goes long on the first point to give Murray a 15-0 lead, before a forehand winner takes him to within two points. It remains at two points when he misses an easy forehand winner, and the Canadian hits his way to 30-30 to increase the tension. The Scot then nets to give Pospisil his first break point of the match but it's saved with a huge serve out wide. Murray has match point after Pospisil sends a forehand long, but it's saved when Pospisil unleashes a big forehand. A second match point is created with a thunderous forehand into the corner, and this time it's taken when his opponent can't handle a forehand.

That last game took a little longer than he would have liked, but Andy Murray has finally booked his place in the semi-finals with a 6-4 7-5 6-4 victory over Vasek Pospisil, who played his part in this match.

Murray will now play Roger Federer in the last four on Friday after the Swiss eased past Gilles Simon. That should be a cracker.

That will be all from Sports Mole for this match, but don't you dare go anywhere. Next up, we have the world number one Novak Djokovic against US Open champion Marin Cilic. Goodbye for now.