West Ham moved a step closer to a first European final for 47 years as Michail Antonio sealed a 2-1 win over AZ Alkmaar in the Conference League semi-final first leg on Thursday.
While West Ham eye a landmark final appearance, FC Basel are chasing history of their own after seizing control of the other semi-final with a dramatic 2-1 victory against Fiorentina.
At the London Stadium, David Moyes' side trailed to Tijjani Reijnders' first half goal before fighting back with a stirring display after the interval.
Said Benrahma equalised with a penalty before Antonio bagged the late winner to put West Ham in control of the tie ahead of the second leg in the Netherlands on May 18.
West Ham have won 12 of their 13 games in the competition this season, taking them to the brink of a first major trophy since the 1980 FA Cup.
Last season, the Hammers lost in the Europa League semi-finals against Eintracht Frankfurt, but they are in position to go further this term.
The east Londoners haven't reached a major European final since they were beaten by Anderlecht in the 1976 Cup Winners Cup showpiece.
West Ham's win against Manchester United on Sunday moved them seven points clear of the Premier League relegation zone with three games left, effectively sealing their top-flight status after a tense survival battle.
That leaves Moyes' men free to concentrate on winning the club's first European trophy since the Cup Winners Cup in 1965.
Despite being one of the smaller clubs in the Dutch Eredivisie, AZ have reached their first European semi-final since 2005.
That success is a tribute to the astute financial model employed by the club's owners, who use the 'Moneyball' philosophy popularised by their minority shareholder Billy Beane during his time running baseball's Oakland A's.
But West Ham had no intention of becoming the latest victims of AZ's underdog story as they recovered impressively from Reijnders' 41st minute sucker punch.
Reijnders unloaded a fierce 25-yard drive that took an awkward bounce as it skipped over Alphonse Areola's misjudged dive.
- Basel fight back -
Areola should have done better and although West Ham protested for a push on Lucas Paqueta in the build-up, the goal stood after a VAR check.
However, AZ had never won on English soil and their hopes of a first victory were dashed in the 67th minute.
As Jarrod Bowen leapt to head over from close-range, Mathew Ryan's attempt to punch clear made contact with the winger's head, conceding a penalty that Benrahma smashed past the AZ keeper.
Roared on by the raucous capacity crowd, West Ham took the lead in the 76th minute as Antonio stabbed in from close-range after Paqueta's header was blocked on the line.
Swiss club FC Basel have even less European pedigree than West Ham, but that could be about to change after they stunned Serie A side Fiorentina.
Fiorentina took the lead in the 25th minute at the Stadio Artemio Franchi when Cristiano Biraghi's corner was flicked on by Lucas Martinez Quarta and Arthur Cabral pounced with a perfectly placed header.
At the expense of his former club, the Brazilian forward's seventh Europa Conference League goal this term made him the tournament's leading scorer.
Basel are a disappointing fifth in the Swiss Super League and have never reached a European final.
But they snatched an equaliser in the 71st minute as a flowing move culminated with Andy Diouf's clinical finish into the far corner from the edge of the area.
In the third minute of stoppage-time, on-loan Inter Milan forward Darian Males teed up Zeki Amdouni for a predatory finish that leaves Basel on the verge of becoming the first Swiss club to reach a European final.
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