This week saw the first legs of the League Cup semi-finals and, at the halfway stage of both ties, all four teams are still very much in with a shout of reaching Wembley.

Tuesday saw a thriller between two English giants as Liverpool welcomed Chelsea to Anfield, and the Blues left having secured a 1-1 draw to take back to Stamford Bridge next week.

There was a winner in Wednesday's tie, but Tottenham Hotspur would have been hoping for a more comfortable lead than the 1-0 one they managed over League One side Sheffield United at White Hart Lane.

Here, Sports Mole picks out five things we learned from the two ties.

When Chelsea booked their place in the last four with a victory over Derby County, they were unsurprisingly installed as heavy favourites to lift the trophy on March 1. The Blues have swept almost all before them this season and are still in with a realistic shout of claiming an unprecedented quadruple.

However, while they escaped Anfield with a draw on Tuesday, there is no doubt that they were very much second best. In the second half especially it was almost one-way traffic for long periods, and Liverpool had chances to win the match and take a lead back to Stamford Bridge. The air of invincibility around Chelsea was somewhat broken by defeats to Newcastle United and Spurs in the Premier League, but even in those matches they rarely went through such a prolonged spell of domination as they suffered at the hands of Liverpool.

The League Cup was the first piece of silverware Jose Mourinho won with Chelsea and, while it may not carry the prestige of the other three trophies they are still in for, it is a vital component of any prospective quadruple. They are a different proposition at home and will enter the second leg as favourites to progress, but that first match will give Liverpool plenty of belief that they can get the job done.

It is fair to say that all three of the Premier League teams left in the competition will have been hoping to draw Sheffield United in the semi-finals. During Wednesday's battle against Tottenham, however, they proved that they would be no soft touch and are very much in the race for a Wembley appearance.

The Blades have been cup specialists in recent seasons, and the defeat at White Hart Lane was just the third that manager Nigel Clough has suffered in 20 cup outings at the helm. They have toppled two Premier League sides already on the way to the last four, one of whom sit above Spurs in the table and both of whom are above Liverpool. They have also beaten Aston Villa, Fulham and Queens Park Rangers from the top flight in the FA Cup within the last 12 months, so will not be daunted by another match against one of the big boys.

A trip to the semi-finals of the FA Cup last season will have whetted their appetite for another Wembley appearance, and they will be fairly content with their position at the halfway stage of the tie. They could have perhaps got a draw from the match, but one error from James McEveley ended up costing them. They are very much in the mix, however, and should they get to the final then anything could happen.

Much was made of Brendan Rodgers's decision to allow Raheem Sterling a mid-season break to Jamaica, but it could end up being a masterstroke by the Liverpool boss. The youngster, who was integral to the team's magnificent run of form in the second half of last season, had looked jaded and far short of his best for the majority of the current campaign.

The 20-year-old has had a gruelling year with the World Cup as well, and Rodgers is rightly wary of burnout for the winger. Special dispensation is often afforded to special talents, and Sterling certainly comes under that category. The initial signs are that the break has done him good too, having put in a man-of-the-match performance against Chelsea, capped off by a sublime solo effort.

He was frustrated for long spells in the first half as Chelsea's blue wall could not be breached, but just before the hour he burst past Gary Cahill and slid the ball into the bottom corner. From then on, Chelsea really struggled to deal with him, and some of his movement and link-up play carried the same swagger that made him such a threat last season. With Daniel Sturridge's return from injury on the horizon too, Liverpool could have a potent strikeforce brewing once again.

When the first semi-final was drawn and only Spurs and Sheffield United were left in the hat, Mauricio Pochettino could be forgiven for rubbing his hands with glee. Even with the Blades' aforementioned giant-killing pedigree, they were by far the least of three evils and gave Spurs the best chance - on paper at least - of reaching the League Cup final for the first time since 2009.

However, they knew they were in a game on Wednesday and can only expect it to be even tougher in next week's return leg. Granted, Tottenham were far short of their best and there is plenty of room for improvement, but credit must also be given to United for the way they stopped Spurs from playing. Their game was full of intensity and desire, and those attributes will be amplified in front of a raucous Bramall Lane crowd.

The tie is, of course, tilted in Tottenham's favour, but only an Andros Townsend penalty separated the two sides in a very even affair at White Hart Lane. You can be sure that Sheffield United will be up for the game, and Spurs will have to match that - and showcase more of their superior quality - if they are to avoid becoming the latest Premier League outfit scalped by the Blades.

Ask any Liverpool fan who their biggest rivals are and the predictable response will be Manchester United and Everton. Likewise with Chelsea, they are likely to point to fellow Londoners Arsenal and Tottenham Hotspur as among their most disliked teams. However, over the past decade the animosity and antipathy between Liverpool and Chelsea has at times approached and surpassed those more traditional rivalries.

The battles between Rafael Benitez and Mourinho have been right at the centre of it, with many infamous incidents during a time when the two sides seemed to clash in every competition. Mourinho's run down the touchline in the 2005 League Cup final, Luis Garcia's 'ghost goal' in the Champions League semi-final and, more recently, Steven Gerrard's slip in last season's crucial league meeting at Anfield immediately spring to mind.

Liverpool's absence from the Champions League and as top-four contenders in recent seasons seemed to dull the rivalry somewhat, but Tuesday proved that it is very much still alive and well. Reports of a bust-up in the tunnel after the match aren't exactly surprising following a game that was played at a frenetic tempo in front of an electric crowd. It is a rivalry both sides seem to relish, and they will renew hostilities once again on Tuesday for what will be their 38th meeting in the past decade.