Unbeaten at home in this competition, Chelsea FC are within sight of their second European final in as many years, but FC Basel 1893 will not give up their UEFA Europa League dream easily, though they have yet to win a game in England.
• David Luiz's stoppage-time free-kick earned the Londoners a 2-1 first-leg advantage after Fabian Schär's late penalty looked to have salvaged a draw for Basel. Victor Moses had headed the outgoing European champions into a first-half lead at St. Jakob-Park. It was Basel's first home defeat in the competition this season.
• The semi-final first leg was the clubs' first competitive encounter.
• In their only previous Swiss assignment, Chelsea lost to FC St Gallen in the first round of the 2000/01 UEFA Cup. They won 1-0 at Stamford Bridge then came unstuck with a 2-0 defeat at the Hardturm Stadium in Zurich. John Terry was an unused substitute in that game.
• Basel eliminated Tottenham Hotspur FC on penalties in the quarter-finals, prevailing 4-1 on spot kicks after two 2-2 draws, but have never won a match in England. Their record in 19 games against English teams reads W3 D7 L9 (W3 D3 L4 in Switzerland – W0 D4 L5 in England).
• Swiss sides are without a victory in their last 18 competitive visits to England (D6 L12) since FC Luzern triumphed 2-0 at Tottenham in the 1995 UEFA Intertoto Cup. Indeed, Switzerland's representatives have won just twice in 29 away matches against English clubs.
• Chelsea are unbeaten in 12 European fixtures at Stamford Bridge (W10 D2) since a 1-0 reverse against Manchester United FC in the 2010/11 UEFA Champions League quarter-finals. They are yet to lose at home in seven UEFA Cup and UEFA Europa League outings (W5 D2).
• Basel have not won an away game in the UEFA Europa League this term (D4 L2).
• None of the four remaining teams have won the UEFA Cup or UEFA Europa League before, with Basel and Fenerbahçe SK both in a European semi-final for the first time. Basel are bidding to become the first continental trophy winners, or indeed finalists, from Switzerland.
• SL Benfica and Chelsea are the only sides left in the competition who transferred from the UEFA Champions League group stage. They will hope to emulate the feat of inaugural victors Club Atlético de Madrid, who won the 2009/10 UEFA Europa League after entering in the knockout phase.
• Basel are the sole reigning domestic champion still in the tournament. They have also played more European matches this season than any other surviving team (19), having begun their continental campaign in the second qualifying round of the UEFA Champions League.
• Basel's David Degen has made more UEFA Cup/UEFA Europa League appearances than any player left in the competition (46).
• His twin brother Philipp Degen played alongside Chelsea's Yossi Benayoun and Fernando Torres during his time at Liverpool FC.
• David Degen and Chelsea's Marko Marin were team-mates at VfL Borussia Mönchengladbach during the 2006/07 campaign.
• Chelsea could become the first side to win UEFA's two top club competitions in reverse order in successive seasons.
• They could also become just the fourth team to win all three of UEFA's major club competitions, after Juventus, AFC Ajax and FC Bayern München. Chelsea lifted the European Cup Winners' Cup in 1970/71 and 1997/98, and the UEFA Champions League last year.
• Frank Lampard (115) has figured in more UEFA club competition games than any player remaining in this UEFA Europa League edition, with Petr Čech (105), Ashley Cole (103) and Terry (101) his nearest rivals.
• Basel's Mohamed Salah, meanwhile, has provided more assists than any player left in the competition, four.
• Goalkeeper Yann Sommer, defender Aleksandar Dragovic and winger Salah have featured in all 13 of Basel's matches since the start of the group stage. Sommer has played all 1,200 minutes of the campaign – more time than any other player still involved this season.
• Čech, Oscar and Torres are the only players used in all seven games of Chelsea's UEFA Europa League challenge, though just Čech and Torres have played all 630 minutes.
• Basel are at their most dangerous after half-time – 12 of their 17 UEFA Europa League goals this term have come after the break, seven of those beyond the 76th minute.
• Basel's success against Tottenham in the quarter-finals was only the second-ever shoot-out in the knockout phase of the UEFA Europa League, after this season's round of 32 tie between FC Steaua Bucureşti and AFC Ajax. In Bucharest, too, the hosts were triumphant from the spot.
• Rafael Benítez moved into coaching at a young age after injury ended his career as a midfielder, taking charge of youth and reserve teams at Real Madrid CF. He led Valencia CF to two Liga titles and the 2003/04 UEFA Cup, and then won the 2004/05 UEFA Champions League with Liverpool. He coached FC Internazionale Milano briefly in 2010/11 and replaced Roberto Di Matteo as Chelsea boss in November 2012.
• Benítez's most recent UEFA Europa League experience came in 2009/10, when he guided Liverpool to the semi-finals before defeat by eventual winners Atlético.
• Benítez has been in the dug-out for 137 UEFA club competition matches – the other three coaches in the semi-finals have presided over just 105 between them.
• Benítez, who prevailed with Valencia in 2003/04, is the only coach left in the competition to have lifted the trophy previously.
• Murat Yakin replaced Heiko Vogel as Basel coach in October. The older brother of fellow former Swiss international Hakan Yakin, he was capped 49 times as a defender and midfielder, and represented Grasshopper Club, VfB Stuttgart, Fenerbahçe SK and 1. FC Kaiserslautern. However, his best seasons came as captain of Basel, helping them to three Swiss championships and two Swiss Cups. He has also coached FC Concordia Basel, FC Thun and FC Luzern.
• Basel's sole previous trip to Amsterdam ended in a 3-0 defeat by Rinus Michels's all-conquering Ajax at the Olympisch Stadion in the second round of the 1970/71 European Champion Clubs' Cup.
• Chelsea have never played a UEFA competition game in Amsterdam, but visited the old Olympisch in the 1968/69 Inter-Cities Fairs Cup – the non-UEFA affiliated precursor to the UEFA Cup and UEFA Europa League – drawing 0-0 with AFC Door Wilskracht Sterk.
Benfica v Basel
• Benfica had the edge on Basel when the sides faced off in last season's UEFA Champions League group stage; the Eagles prevailed 2-0 in Basle, Cardozo scoring the second goal, then drew the return fixture 1-1 in Lisbon.
Basel v Fenerbahçe
• The teams have never met in UEFA competition. Fenerbahçe boast a notable Swiss talent in defender Reto Ziegler, who started his professional career with Grasshopper-Club and has played 32 times for Switzerland.
Chelsea v Benfica
• The clubs' sole previous encounters came in last year's UEFA Champions League quarter-finals, with the Londoners winning both legs – 1-0 in Lisbon and 2-1 in the English capital. Benfica midfielder Matić joined the Eagles following a spell at Stamford Bridge.
Chelsea v Fenerbahçe
• Chelsea battled their way past Fenerbahçe in the 2007/08 UEFA Champions League quarter-finals; Avraam Grant's men went down 2-1 in Istanbul but turned things around with a 2-0 triumph at Stamford Bridge. Fenerbahçe's Miroslav Stoch and Meireles are former Chelsea players.
• Chelsea's UEFA shoot-out record reads W1 L2:
W 4-3 (neutral) v FC Bayern München, 2011/12 UEFA Champions League final
L 5-6 (neutral) v Manchester United FC, 2007/08 UEFA Champions League final
L 1-4 (away) v Liverpool FC, 2006/07 UEFA Champions League semi-final
• Basel won their first UEFA penalty shoot-out in the last round:
W 4-1 (home) v Tottenham Hotspur FC, 2012/13 UEFA Europa League quarter-finals
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