Basel v Chelsea
This is Basel's first ever appearance in a European semi-final.
Chelsea, meanwhile, have made 11 previous semi-finals in European competition, making the final on four occasions.
Chelsea's one previous encounter with Swiss opposition in Europe (excluding qualifiers) saw them lose 1-2 on aggregate to St Gallen in the 2000/01 UEFA Cup first round.
Basel's victory over Tottenham was their first ever knockout victory over an English side; they had previously suffered defeats to Newcastle (UEFA Cup 2003/04) and Middlesbrough (UEFA Cup 2005/06).
In terms of individual matches, Basel have only won two of 15 games against English sides (2-0 v Middlesbrough in March 2006 and 2-1 v Manchester United in December 2011).
Chelsea have lost consecutive away games in Europe; they have not lost three in a row (excluding qualifiers) since May 2005.
This match will be Chelsea's 62nd of the season in all competitions.
Basel are unbeaten in their last eight home games in Europe, winning six and drawing two.
The Swiss side have scored six goals from corners in the Europa League this season, a competition-high.
Fenerbahce v Benfica
Benfica's only previous European tie against Fenerbahce saw them win the first leg 7-0 on home soil, eventually progressing 7-1 on aggregate, these games coming way back in 1975.
Indeed, Benfica have never scored a goal in an away game against a Turkish side (played two, one 0-1 defeat and one 0-0 draw).
This will be Benfica's 13th appearance in a major European semi-final; After winning eight of their first 10, they have lost the last two in a row (1994 CWC and 2011 EL).
Fenerbahce are making their first ever appearance in a major European semi-final.
The Turkish giants have won 12 and lost just two of their last 19 European games (D5).
Fenerbahce have kept seven clean sheets in their last 10 European games.
Benfica are unbeaten in nine European games, winning seven and drawing two.
Oscar Cardozo has scored six goals in Europe this season, despite making just five starts (11 appearances in total).
The Paraguayan striker has scored 17 goals in the Europa League since it was rebranded ahead of the 2009/10 season; only Falcao (30) has more.
No team in the Europa League has kept more clean sheets this season than Fenerbahce (seven).
