Three of the last four of the 2016-17 CONCACAF Champions League are known: Pachuca and FC Dallas will contest one semifinal; Tigres UANL is waiting for the winner of this quarterfinal between Vancouver Whitecaps and New York Red Bulls.
Vancouver holds the advantage after the first leg. The 1-1 tie at Red Bull Arena gave the Whitecaps an away goal - and away goals are the tiebreaker if the teams are still level after 90 minutes of the second leg. So RBNY has to score in this game to have any chance of getting to the semifinals.
A win for either side inside 90 minutes is a win overall and a place in the next round for the second-leg victor. If the score is 0-0 after 90 minutes, Vancouver wins on away goals. If the score is 2-2 or any higher-scoring draw, RBNY goes through on away goals.
If the teams tie the second leg as they did the first, 1-1, then the match will go to extra time - and there is no away goal advantage in extra time. If no outright winner emerges from extra time, then penalties will decide which side is a semifinalist.