Aston Villa v Bradford City
Villa's defeat away at Bradford in the first leg was their first-ever League Cup defeat to a side from the fourth tier (W23, D4).
In the first leg Villa racked up 11 shots on target, more than they have managed in any other game (in all competitions this season) but could only score one goal (Bradford had eight on target and bagged three).
The Bantams have a fine record in penalty shootouts in recent cup and knock-out competitions, winning their last nine shootouts, notably defeating Arsenal and Wigan in this year's Capital One Cup.
If Bradford can progress to the final, they will be the first fourth-tier side to defeat three top-flight teams in the same League Cup competition.
Villa have one victory in five home games in all competitions (L3 D1).
The Bantams are without a win in five away games, losing three and drawing two.
Only Theo Walcott has scored more goals in the League Cup this season than the in form Bradford striker Nahki Wells (three goals), he also has 13 in League Two this season.
Should Bradford progress it will be their first major cup final since 1911, when they managed to win the FA Cup beating Newcastle 1-0 when the final was replayed after a 0-0 draw.
Villa last reached the League Cup final in 2010, eventually losing 2-1 to Manchester United. It was the eighth time the Villans have made it to the final.
Villa have never been knocked out at this stage by lower league opposition, winning all three previous ties against lower league sides.
Swansea City v Chelsea
Swansea's 2-0 victory in the first leg ended a run of five games without a win over the Blues in all competitions.
It was also Swansea's first clean sheet in the League Cup away from home since 1993/94, a run of 19 games.
Should Swansea reach the final it will be the first time in their history. Before this season, the Swans had never progressed past the fourth round.
The last time Chelsea trailed by two goals going into the second leg of a League Cup semi-final was against Sheffield Wednesday in 1991 (lost 2-0) and they were eliminated 5-1 on aggregate.
The Blues have scored three or more goals in five of their last eight away games in all competitions.
Chelsea have a great history in this competition, reaching the final on six occasions, winning four times, two of which triumphs have come since 2007.
Juan Mata has scored two goals and assisted four more in just five League Cup appearances for Chelsea.
