The Montreal Impact are through to the Concacaf Champions League semifinals after one of the most dramatic finishes imaginable.

Cameron Porter’s 94th-minute strike off a long-distance assist from Calum Mallace lifted the Impact to a 1-1 draw with Liga MX side Pachuca on Tuesday and saw them advance on the away-goals tiebreaker. The teams had battled to a 2-2 deadlock last week in Mexico.

While Pachuca dominated possession throughout Tuesday’s return leg, the Impact still managed nine shots on goal – none more crucial than Porter’s last-gasp winner, which ignited pandemonium among the 38,104 fans at Montreal’s Stade Olympique.

Porter, a Princeton alum chosen in the third round of January’s MLS SuperDraft, had come on as an 85th-minute substitute for midfielder Nigel Reo-Coker.

“Sheer ecstasy,” the 21-year-old rookie told the Canadian Press. “I didn’t even know how to celebrate so I just started running, basically. And everyone piles on top of you and you find it hard to breathe.”

German Cano had seemingly assured Pachuca’s progress with an 80th-minute penalty kick, a goal that merely set the stage for Porter’s heroics.

Montreal will face the winner of the quarterfinal tie between DC United and Costa Rican side Alajuelense, who play on Wednesday at RFK Stadium in Washington. Alajuelense leads 5-2 after one leg.

With the win, the Impact became the first Canadian side to win a two-legged tie against a Mexican opponent.