Justin Cooper took Superpole in the SX1 class as he beat fellow big guns Eli Tomac and Ken Roczen.
This contest was being billed as defending champion Tomac versus former world champ Roczen, who dominated in Round 1, winning all three races.
But it was Cooper who excelled in tricky conditions, as the track at BC Place started to break up.
He said: “The track was really beat up, but I had to stay consistent, keep momentum, and survive.
“I am trying to spice it up as a wildcard against two multi-time champions. I am trying to keep up with them and give them a run for third money.”
Cooper was 0.753 sec ahead of Tomac, who was making his debut on a KTM. The American had looked strong in practice but could not set a time that was quick enough to beat Cooper.
Tomac was second and got his second gate pick, while Joey Savatgy was third for Quad Lock Honda.
Roczen, who came into the round as championship leader, had to settle for fourth in what is shaping up to be an epic battle for the winner of the round.
In the 250cc SX2 class, Max Anstie again took Superpole, just as he had done in the Buenos Aires City GP.
Anstie was in a class of his own in Argentina and again was unstoppable in the top-four shootout with a time of 57.335.
The Team GSM powered by Star Racing Yamaha rider said: “It was tough for Superpole on the track.
“You have to be comfortable being uncomfortable, and the goal was to be better than last week. This world championship mean a lot to me, and I am excited to be here.”
Anstie crossed the line ahead of Rick Ware Racing duo, City Schock and Enzo Lopes, who were second and third, respectively.
Cullin Park, who picked up a penalty in Buenos Aires for breaching sound levels on his MotoConcepts Racing Honda, was fourth quickest.
