The Spaniard surrendered the opening set but hit back in the next and then raced to 5-2 in the decider before squandering match points to hand big-serving Hurkacz a lifeline.

But Alcaraz quickly recovered to close out the victory via a tiebreak to reach the quarter-finals.

"Honestly, I didn't know what happened," Alcaraz said of his loss of form during the final set in Toronto. "I started feeling bad in that moment.

"I couldn't feel the right way in my shots. What I was thinking was to stay calm, try to find a way to overcome the problems and find the good feeling again. I think at 5-6 serving, I started to feel better.

"The big players have that feeling to find a way to stay alive and try to end the match playing well."

Wimbledon champion Alcaraz, who extended his winning streak to 14 matches, next plays 12th seed Tommy Paul, and the Spaniard is not keen to rein in his swashbuckling style as he warms up for the US Open starting later this month.

"In the tough moments you have to believe in yourself, try to go for it," said Alcaraz, whose approach has been described by former world number one Andy Murray as "kamikaze" at times.

"It doesn't matter if you win or not. You have to believe you are going to play your best in that moment, try to play aggressive. I think in the two tie-breaks I did pretty well. That's why I got the win."