West Ham United substitute Pablo Fornals scored a breakaway goal in stoppage time as the visitors secured a 1-0 win at AZ Alkmaar on Thursday and a place in the Europa Conference League final after a 3-1 aggregate triumph.
The Hammers are through to a European club competition final for the first time in almost a half century after a 2-1 win in the first leg in London last week and the last-gasp 1-0 triumph in Thursday's return leg against the Dutch side.
They will now take on Fiorentina in the final in Prague on June 7.
West Ham, who won the European Cup Winners' Cup in 1965 and were runners-up in 1976, put up a dogged showing despite looking tired and spending much of the time chasing their opponents.
But they were stout in defence and already playing for time near the end of the game when Fornals broke away in the fourth minute of stoppage time to win the game.
AZ put up a brave showing but the difference in class between the Premier League outfit and their Dutch opponent was evident as West Ham dealt with everything their hosts threw at them.
There was a scare late in the game when the ball hit the hand of Kurt Zouma after being punched clear by his own goalkeeper Alphonse Areola but despite home protests no penalty was awarded.
Lucas Paqueta hit the outside of the post in the first half while AZ looked passive in the opening period, despite rowdy support, but came out with vigour after the break, making dangerous runs and delivering inviting balls into the West Ham penalty area but failing to find a decisive touch.
Jarrod Bowen had a breakaway chance in the 74th minute but his pull back in search of a team mate was cleared, while at the other end there was an anxious clearance by Areola after a back pass from Thilo Kehrer looked to be heading into his own net.
Defender Nayef Aguerd then put the ball wide when unmarked at the back post with seven minutes remaining before the last gasp winner.
"His name is going to be written in West Ham history forever. He's so happy," said captain Declan Rice of Fornals' achievement.
"We're absolutely thrilled. It's a big achievement for the club, but now it's about going and winning it," added manager David Moyes.
"AZ played a really good style, the Dutch football is really good. They gave us a shock in the first leg, and I knew if I didn't set us up in a deeper block they could punish us."