Kei Kamara atoned for a missed penalty by netting an extra-time winner as Columbus Crew beat Montreal Impact 3-1 to set up an Eastern Conference final date with New York Red Bulls.
The 31-year-old, who also opened the scoring, struck with nine minutes of the additional 30 remaining at the Mapfre Stadium as Gregg Berhalter's side advanced with a dramatic 4-3 aggregate victory.
Trailing 2-1 from last week, the hosts needed only four minutes to level up the tie as Kamara headed home a Waylon Francis cross to stun the visitors early on.
Kamara continued to run amok and then headed Harrison Afful's delivery against the crossbar as Columbus looked to improve on their fast-and-furious start.
Montreal were reduced to long-range efforts in a half which saw them fail to get behind the hosts' defence, with Ignacio Piatti firing narrowly over the bar on the half-hour mark.
However, Dilly Duka secured parity at the break by turning the ball home from close range on 40 minutes after the Crew failed to clear their lines from a corner.
The Canadian side looked the more dangerous after the break, with Didier Drogba denied by goalkeeper Steve Clark, before Piatti drilled wide once more as the visitors grew in control.
Columbus slowly but surely wrestled the momentum off them, with the hosts earning a penalty on 68 minutes when Laurent Ciman fouled Ethan Finlay, but Kamara failed to beat Evan Bush from 12 yards.
It was Finlay who spared his teammate's blushes by smashing home into the roof of the net with 12 minutes to play as Berhalter's side forced extra time.
A cagey first half passed without incident, before Kamara headed home Cedric's flick-on at the near post to seal their progression into the finals.
Shane Callaghan
