Looking to reach a European final for the first time in 47 years, the Hammers endured a frustrating first-half at the London Stadium as Tijjani Reijnders fired the visitors in front, with Lucas Paqueta perhaps fouled in the build-up and goalkeeper Alphonse Areola poor in letting the shot beat him.
But West Ham responded after the break, as Said Benrahma levelled it up with a confident penalty before Michail Antonio continued his strong goalscoring form in the competition to put the hosts in front and give them a narrow lead at the halfway stage.
It’s still all to play for next week when the teams meet again in the Netherlands, with Fiorentina or Basel waiting for the winner in Prague on June 7.
The performance on the pitch from West Ham did not necessarily match the energy coming from the stands, as the hosts, on the whole, were happy enough to sit back and let AZ have possession. They looked most dangerous when the visitors played their way into trouble, with Said Benrahma pouncing on one loose pass and forcing Mat Ryan into a superb save.
It was AZ who took the lead heading into half-time though, and in controversial fashion. Paqueta appeared to have been shoved, certainly by the standards set by the referee earlier in the match, but play was waved on and AZ broke. Reijnders let fly from distance, Areola should have done much better but the strike was allowed to bounce into the bottom corner.
Neither side looked particularly likely to trouble the scoreboard in the opening 20 minutes of the second-half, West Ham increasingly direct but having nothing to show for it. They were gifted a way back into it though, as Jarrod Bowen was cleaned out by Mat Ryan as he flicked a header at goal, and the referee wasted little time in pointing to the spot. Ryan guessed correctly, but Benrahma’s penalty was hammered beyond him.
Within ten minutes, the Hammers were in front. Declan Rice dinked the ball back into the box after AZ failed to clear a corner, Nayef Aguerd’s effort was just about kept out on the line but Antonio was on hand to bundle home from close range and swiftly end any goalline technology complaints. Both teams though will still fancy their chances of getting the job done in seven days’ time.