Piastri qualified third behind George Russell and Max Verstappen, while Norris was further back in seventh — his worst qualifying result since Saudi Arabia.
It’s also the first time McLaren will not start from the front row in 2025.
Speaking to Sky Sports F1 after qualifying, Stella admitted the weekend had been challenging, with the team making several changes across the event.
“This weekend could be one of damage limitation,” he said.
“We needed to make a lot of changes, for stability in particular. We were competitive, with Oscar we maximised what we had.
“Verstappen and Russell are fast, but with Lando, quick in Q1 and Q2, but the new tyres in Q3, we lost some of the rhythm and we have some work to do tomorrow.”
McLaren brought several upgrades to Canada, including changes to the front wing and suspension. Both Piastri and Norris trialled the new front wing on Friday, while Norris is the only one running the updated suspension.
The Brit said he hadn’t felt any difference with the new suspension and admitted to making too many errors during qualifying.
During his first run in Q3, Norris made a mistake under brakes and skipped the final chicane.
“I hit the wall in the last lap,” Norris told Sky Sports F1. “I had good confidence, the car felt good today, I just made too many mistakes.
“We’ve clearly not had our advantage around this track, you need a very good ride. I think our pace is good enough, (we’re) just too far back again.”
The last time a driver won the Canadian Grand Prix without starting from the front row was Daniel Ricciardo in 2014, who won from sixth on the grid.
The Formula 1 Canadian Grand Prix gets underway at 4am AEST on Monday.
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