Good evening everyone. Rafael Nadal may have already secured his place in the semi-finals in London but his job in Group A is not finished yet. The Spaniard puts on his gear tonight to face Tomas Berdych, who must win to qualify for the final four.

It's a huge game for Berdych but it's also a big match for someone not even involved. Stanislas Wawrinka beat David Ferrer earlier today and it is he who will benefit if Berdych fails to record a victory tonight.

Berdych's task could not be more difficult. Nadal has ensured that he will be the world number one at the end of the season and his form this year has been absolutely outstanding. The Spaniard just seems to be getting better and better.

Nadal's fate has been decided but Wawrinka will be hopeful that he doesn't take the foot off the gas at the O2 Arena. To be honest, I can't see that happening. Nadal brings his all every time he steps on the court.

Berdych's first target will be to take a set off Nadal, which is something that hasn't happened yet this week. The Czech player has shown in the past that he can produce his best on the big stage.

Berdych heads into this match on the back of a straight sets win over Ferrer on Wednesday. However, he started the week with a loss to Wawrinka in three sets.

Nadal needed two tie-breaks to beat Warwinka in his second match following a routine straight sets triumph on Tuesday over Ferrer, who has failed to produce his best this week.

The players will take to the court in around 10 minutes for the crucial Group A game. It promises to be a very exciting evening in London. Can Berdych shine tonight?

Nadal is desperate to end a great year by claiming victory in this tournament. Novak Djokovic and one other member of Group B also stand in his way to the trophy. This one isn't over yet.

The atmosphere is building inside the O2 Arena as more spectators take their seats. It's a wonderful venue for an event like this and I think the ticket buyers will be treated to some great tennis.

Nadal is loosening up in the corridors while listening to some music as he prepares for his final group game. He plays a big role tonight and he could be the one who decides which player joins him in the semi-finals.

Berdych tells Sky Sports: "I'm definitely in a better position than i was after my first match, so I'm ready to got. I will try to stick to my game and be aggressive."

"I need to play my best against an opponent who is trying to qualify for the semi finals. I will try to play best match. He's a great player and I feel that if I am not playing my best it will be impossible to win," Nadal reveals to Sky Sports.

These two players have met each other on 19 occasions in the past. Nadal has won 16 of those games, with Berdych only claiming victory three times.

Both men are greeted with a warm reception but the cheers are slightly louder when Nadal walks onto the court. Berdych, as ever, looks very relaxed out there.

After a coin toss and a slightly awkward photo in the middle of the court, the players the retreat to the baseline to knock up. Berdych will serve first.

Is it possible to make the best forehand in the world even better? Apparently so, Nadal has proved this season. Berdych must find a way to deal with that threat this evening or he will be quickly put on the back foot.

Remember, if Tomas Berdych can win in straight sets tonight he will be the winner of Group A. That would be a dream night for the Czech, who will only be caring about the victory.

All of the final preparations have been made now and we're almost ready for some tennis. The excitement is obvious inside the O2 arena. Berdych will get the match underway.

BREAK! Nadal wins the first point of the match with a stunning forehand to leave his opponent helpless at the back of the court. The Spaniard repeats the trick once again as he follows a couple of sliced backhands with a second forehand winner. An unsuccessful challenge follows. Berdych gets his first point on the board with a well placed forehand of his own moments later. The Czech then offers Nadal two break points when he hits a shot far too long. A big serve saves the first one as Nadal fails to get his return to land in. However, a wild forehand from the sixth seed goes out and another challenge confirms the break of serve.

Great start from Nadal as two big serves give him a 30-0 lead. Berdych battles well to stay in a long rally and he's rewarded when his opponent commits an unforced error. The Czech then finds the net twice in the next two points to lose the game.

Nadal spots an opportunity when Berdych drops his length but the Spaniard misses the line with a big forehand. Some big ground strokes from Berdych help him go 30-0 up but he gifts a point back with a wayward backhand. The scores are level when the sixth seed delivers a double fault. Berdych responds in perfect fashion when he fires in a 137mph ace, but the game is won by some superb play at the net.

Nadal hasn't quite found the rhythm on the backhand yet as he finds the net early in a new game. Berdych has been even more disappointing on his forehand and an unforced error makes it 15-15. A slow second serve offers Berdych a good opportunity but his backhand lands wide. Nadal plays a couple of devastating forehands to win the next point as he begins to move his rival around the court. Berdych then fires a forehand wide to hand the game to the world number one.

Excellent play from Berdych as he sends his opponent the wrong way to execute a forehand winner. An unforced error makes it 30-0 but Nadal quickly fights back with a low forehand which proves to be impossible to return. It's 30-30 when Nadal pounces on a short serve to unleash a brilliant forehand winner. The Spaniard slips as he unsuccessfully attempts to repeat the rick. Berdych strikes a forehand long to make the scores level again. However, a wayward slice from Nadal gifts the advantage to the Czech. An ace ensures Berdych only remains a break behind.

A big serve is followed by a superb forehand as Nadal starts a new game confidently. Another big serve is impossible for Berdych to return. The Czech pulls a point back but he falls further behind when his backhand sails out. Nadal unleashes another big serve to win the game. Very impressive.

Nadal takes the lead early in the game but a huge ace makes it 15-15. Berdych should win the next point with a routine forehand but he fires the ball wide. Nadal manages to get racket on the next ball but he can't continue the rally. Berdych forces the Spaniard onto the back foot in the next exchange to move 40-30 ahead. The game is won when Nadal hammers a backhand into the net.

Amazing. Berdych barely gets his return to make it over the net but Nadal somehow drills a forehand into the net. The Spaniard quickly readjusts to unleash a winner with his next opportunity. Berdych continues to struggle to return the serve down the middle as Nadal moves 30-15 ahead. However, a double fault offers an opening for the Czech. Poor from Berdych as he sends an easy backhand well wide of the line. Nadal produces another brilliant forehand to take full advantage. Berdych will serve to stay in the set.

Much better from Berdych as he ensures that Nadal will have to serve for the set by holding to love. There's been some signs of resistance but he hasn't produced that often enough.

SET! A big serve makes life difficult for Berdych and it's 15-0. Nadal is furious with himself when he hands a point back with a wild backhand. The Spaniard follows another excellent serve with an inch-perfect forehand winner to take a 30-15 lead. An ace then brings two set points. Nadal only needs one though as a Berdych unforced error gives him the first set.

Berdych faces a tough battle to reach the final four from this position. He has now lost 13 sets in a row to Nadal, who probably still has a lot more to offer in this match. Wawrinka might just be breaking a smile in his hotel room.

Berdych serves first in the second set. He must be aggressive from the start here or an exit from the tournament will come sooner rather than later.

The sixth seed races into a 40-0 lead with three massive which Nadal is unable to return. Berdych then secures the game with an ace straight down the middle. That's an excellent start to the second set.

BREAK! Nadal breaks down his opponent with a string of powerful backhands to win the first point in a new game. However, the Spaniard is forced further back during the next rally and he sends a backhand long. Berdych somehow manages to stay in a marathon rally and he is rewarded when he forces Nadal into an awkward position, which then hands him the point. Superb! Berdych is certainly being aggressive now as he unleashes a forehand winner to claim two break points. Nadal saves the first of a couple with an ace down the middle. Berdych does it! Nadal can't find the line with the forehand and the advantage is with the Czech player in the second set.

Nadal's frustration is clear when he hits another forehand wide. Berdych's confidence continues to improve when he serves an unstoppable ace. Another big delivery is too powerful for Nadal to return and an unforced error from the Spaniard allows Berdych to hold to love again.

BREAK! Nadal intends to come forward following a second serve but a clever forehand from Berdych surprises the Spaniard, who loses the first point. A wild forehand sees the world number one fall 0-30 behind. Stunning tennis from Berdych as he takes control early on in a long rally and his powerful backhand brings an error from Nadal. The sixth seed now has three break points. Brilliant! Berdych takes a 4-0 lead in the second set with a gorgeous forehand winner.

Berdych wins the first point of a new game but Nadal fights back with a superb return winner. The Czech responds with a couple of 130mph aces to take a 40-15 lead. Nadal forces the issue when he approaches the net and that causes Berdych to find the net. However, the sixth seeds holds his nerve to claim the game with another big serve out wide.

Nadal, serving to stay in the set, takes a 15-0 lead with a textbook smash. Berdych then miscues a return of serve to fall further behind. Nadal gets himself into an awkward position and he's forced to play a double-handed backhand, which hands the momentum to Berdych and the Czech ace makes no mistake to win the point. The world number one then produces an ace at a vital stage before winning his first game of the set with a classy volley. Berdych will now serve for the set.

Berdych's backhand clips the top of the net and that allows Nadal to take his time before unleashing an unstoppable forehand. The Spaniard shows some fight with an even better forehand to leave Berdych helpless at the back of the court. Nadal continues to be aggressive but he fails to beat the net when attacking the second serve. A couple of aces arrive at a perfect time to bring up a set point for Berdych. The Czech chooses to challenge on the vital point but Hawkeye shows that Nadal's forehand landed on the line. Nadal once again finds the net with a backhand when returning the second serve and a second set point is accepted by Berdych, who levels the scores with an ace. What a stunning set of tennis from the sixth seed!

Wawrinka will be sitting slightly less comfortably now. Where did that come from? Nadal didn't look like the same player in that set but Berdych produced some brilliant tennis. Who will claim the advantage at the beginning of the decider?

The confidence is flowing for Berdych as he dominates a rally before being gifted a point via an unforced error from Nadal, who responds well to make it 15-15. A big serve is followed by a trip to the net and Nadal takes the lead. Berdych is forced to sprint across the whole of the baseline to reach the ball in the next rally but he can only find the net with his forehand. Nadal loses another point due to a poor backhand and a miscued forehand brings deuce. Berdych hits the net to hand the advantage to his rival but he makes up for the error with a brilliant forehand winner. Nadal matches the Czech's effort in the next point before claiming the first game of the third set when Berdych strikes the net.

Vintage Berdych as he follows a big serve with a drilled forehand effort at the net to take a 15-0 lead. A double fault gifts a point to Nadal but the advantage is Berdych's again when the Spaniard finds the net with his return of serve. Nadal can't find the line with his backhand on the run and an ace then secures the hold for Berdych.

Berdych sends his opponent the wrong way with a forehand which Nadal would have been proud to play. Nadal moves ahead in the game thanks to a couple of big serves. A miscued forehand from Berdych makes it 40-15 and the world number one closes out the game with a classy forehand winner.

Berdych combines a big serve with a perfect forehand to win the first point of a new game. A similar effort follows but the ball drifts just wide on this occasion. Berdych reacts well when the ball clips the top of the net to leave Nadal helpless to stop another forehand. Nadal shows great spirit to stay in a rally after being on the back foot but a sloppy sliced backhand makes it 40-15 to Berdych. One point is handed back to the Spaniard but Berdych then wins the game with an ace.

No drama for Nadal in his latest service game as he holds to love. There's not much in it at the moment and a solitary break may well be enough.

A clip of the net counts against Berdych as the deflection carries the ball wide. The Czech ace recovers well though to level the scores with a beautiful forehand winner. Nadal goes too hard with the backhand and the lead is with Berdych, who makes it 40-15 when his big serve proves too hot to handle for the Spaniard. A backhand into the net from Nadal ensures the third set continues to go with serve.

Nadal starts the game with two big serves, with the first earning him a point. However, Berdych produces a superb return of the second delivery to push Nadal back and claim a point. The crowd are delighted when Berdych unleashes a flurry of excellent shots before finishing the rally with an emphatic volley. Nadal calms fears in his camp by securing the next two points with a big serve and a superb forehand winner. Berdych then returns a second serve long to hand the game to Nadal.

BREAK! A couple of errors early in the game from Berdych hands a 0-30 lead to Nadal. The crowd sense that a breakthrough might be about to arrive and the volume increases even further when Nadal brings up three break points with an unstoppable forehand winner. Berdych saves the first one with a good volley following an approach to the net. Oh no! Berdych loses the game on a double fault and Nadal will now serve for the match.

GAME, SET, MATCH! Nadal is a step closer to victory when Berdych finds the net with his forehand. The Spaniard moves further ahead when a frustrated Berdych fires a backhand wide. Another unforced error gifts three match points to the world number one. Nadal wins! The inevitable is delayed when a double fault is delivered but it doesn't take much longer for Nadal to secure the triumph thanks to a stunning forehand winner.

Nadal beats Berdych 6-4 1-6 6-3 to knock the Czech ace out of the World Tour Finals. Berdych produced some brilliant tennis in the second set but a sloppy service game in the decider handed the victory to the world number one.

Berdych's despair is Wawrinka's joy. The seventh seed progresses into the semi-finals by securing second spot in Group A thanks to Nadal's win tonight.

Berdych will return home and think about what could have been after Nadal ended the Czech's participation in the tournament for another year. The world number one marches on with an unbeaten record.

Thanks for joining me this evening and make sure you return to the site as we bring you coverage of the remaining games in the World Tour Finals. Goodnight.