Auger-Aliassime, the fourth seed from Montreal, had 21 aces to six for Hurkacz and hit 38 winners, 16 more than his opponent.
But in a match where both players did an excellent job holding serve — Auger-Aliassime did not face break point, and Hurkacz saved the only one he faced — Hurkacz made the most of his opportunities in the set tiebreakers.
Down 2-1 in the first tiebreaker, Hurkacz won six straight points to claim the set. The fifth seed form Poland didn’t trail in the second tiebreaker and forced four errors from Auger-Aliassime.
Hurkacz will next face Australia’s Nick Kyrgios, who beat Spain’s Pablo Carreno Busta 6-4, 6-2 in the quarterfinals.