Sonoma IndyCar: Will Power claims season finale pole for Penske

On a day where the previous record of 1m17.1s - also held by Power - had already been reset to 1m16.8s by Ryan Hunter-Reay in practice, Power found another 0.6s to put the new marker at 1m16.2597s.

Remarkably, he set the time on a set of stickered black tyres, rather than on the softer-compound reds that usually come to the fore in qualifying.

"Our strategy was to do two runs on the used reds but then Josef did [a run on the blacks] and went quicker, so we had no choice," Power said.

"If [Newgarden] had done it at the end, he would have got pole. He kind of showed us the way."

Until Power's last-minute lap, Josef Newgarden appeared set to make first place his own after clocking a 1m16.3964s just before the end of the session.

"Getting pole would have helped [my title hopes]," said Newgarden, who still has an outside chance at the championship.

"That was really disappointing at the end there.

"Power did a great job, he's incredible around here, but I thought we might have had something for him. That was tough. We have a really good car."

Hunter-Reay was third-fastest alongside Simon Pagenaud, while Montoya's gamble on not leaving the pits until the final three minutes failed to lift him any higher than fifth.

"We have to be smart, we have to be patient and see what it brings," he said.

Rahal, meanwhile, conceded that starting alongside Montoya will give him more work to do in the race, although he is optimistic that having done his qualifying run on the reds could translate into an advantage when he has an extra set of new tyres on Sunday.

"We changed [the car] quite a bit but we've been struggling to get a good balance here this weekend," he said.

"I'm disappointed to be sixth but tomorrow is a new day.

"The car was pretty good on new tyres but on the second run we had a lot of fall-off. I don't know why.

"And a lot of guys were using the new blacks for some reason and we have another set for tomorrow, so either they're making a wrong move or we are."

Of the six remaining championship contenders, the two with the most to do are Scott Dixon and Helio Castroneves.

Dixon had made it through to the second phase but had his best lap ruined when he encountered dirt all over the track at Turn 6, leaving him to start from ninth.

Castroneves, meanwhile, failed to make it out of the first group, and his title hopes now hinge on how well he can recover from starting 15th.

QUALIFYING RESULTS:

CHAMPIONSHIP CONTENDERS: