West Ham 1-2 Eintracht Frankfurt
(Antonio 21' – Knauff 1', Kamada 54')
London Stadium

Eintracht Frankfurt coach Oliver Glasner had called on his players to show their "Europa League face" before they embarked on their second semifinal in the tournament in four seasons – and his players delivered against West Ham with a victory that gives them the edge ahead of the return leg in Frankfurt next week.

"It was a concentrated performance and we performed with courage, there were lots of positive emotions,” Frankfurt goalkeeper Kevin Trapp told broadcaster RTL. "We know that we can contest such games, today was another highlight for us. To make it perfect at home would be one of the most beautiful victories."

Frankfurt remain unbeaten in 11 games in Europe this season, winning at Real Betis and most memorably in Barcelona. West Ham, who themselves had seen off Lyon to reach this point, join that list as the Europa League continues to liberate Frankfurt from an inconsistent Bundesliga campaign. On the road in Europe, Frankfurt hit heights that could see them reach their first European final since 1980 - the same year West Ham last won silverware. 

Dream start for Knauff

Glasner's battle cry ahead of kickoff was answered inside a minute when Frankfurt silenced a coruscating atmosphere inside the former London Olympic Stadium, taking the lead inside a minute. A deft turn on the edge of the box and a flighted deep cross by Rafael Santos Borre was met on the run by 20-year-old Ansgar Knauf, who nodded in before leaping for joy in front of the stunned home fans.

It was his second goal in the competition this season following his strike against Barcelona in the quarterfinal and another reminder that his acquisition on loan from Dortmund has been a shrewd piece of business.

West Ham's Jarrod Bowen was the hosts key attacking threat and he hit the post and later the bar with a sensational overhead kick. West Ham drew level through Michail Antonio though, with the Jamaica international putting the ball in from close range.

Frankfurt had the last laugh through, with Daichi Kamada – the hero against Arsenal on Frankfurt's previous trip to London – putting the ball in after Djibril Sow's initial effort was kept out. Frankfurt survived a late West Ham onslaught to give them the edge in this gripping contest, ahead of the return leg on May 5.

Frankfurt president Peter Fischer was in London too, and his reaction summed up a memorable evening for the Hessians. "I am speechless," he exclaimed. "I think we deserved the 2-1 but we know it's only halftime."