Helio Castroneves boosted his title hopes by securing pole for Fontana's IndyCar finale, while a catastrophic session for Will Power leaves the points leader at the rear of the field.
Castroneves was the last driver to make his qualifying run and delivered a 218.540mph two-lap average to give himself the top starting spot for Saturday night's title-deciding race.
Juan Pablo Montoya's early run of 217.621mph was enough to secure a Team Penske 1-2 on the grid.
"This certainly helps," Castroneves said. "But it's not everything. Will and JP [Juan Pablo Montoya] went out ahead of me and I was able to see their data and make a final adjustment. It wasn't much, but it was enough to get pole.
"But tomorrow is a 500 mile race. Our job is to attack and be aggressive, and finish in the same position we started."
When Power completed a warm-up lap in the 216mph range he appeared destined to be somewhere up there with his team-mates, but two awful flying laps left the Australian back in 21st with an average speed of only 212.604mph, and facing a busy evening on Saturday.
"[The car was] too loose," he said. "You've got three hours to work your way to the front [in the race]. I think that's going to be the mindset.
"A big plus is that it's a track you can pass on. Hopefully it will be cool enough that we have multiple lanes, and we can make our way through."
Power now leads Castroneves by 50 points, with 100 on offer for the win in the double-points event.
Simon Pagenaud, who is the only other driver with a mathematical chance at the title, will start from 13th. He trails Power by 81 points.
Temperatures spiked substantially from practice earlier in the day, and the very warm conditions caused problems for several drivers.
But they were little cause for concern for Josef Newgarden, who finished up third-fastest for Sarah Fisher Hartman Racing and was convinced that he could have been on pole had he chosen a better line for his first flying lap.
Others who were left ruing what might have been were Takuma Sato, who was first after his first flying lap but fell to fourth after a slower lap two, and Ed Carpenter, whose similar second-lap fade left him back in 14th.
Pos Driver Team/Engine Speed 1. Helio Castroneves Penske/Chevy 218.540 2. Juan Pablo Montoya Penske/Chevy 217.621 3. Josef Newgarden Fisher/Honda 217.600 4. Takuma Sato Foyt/Honda 217.323 5. Scott Dixon Ganassi/Chevy 217.057 6. Charlie Kimball Ganassi/Chevy 217.017 7. Tony Kanaan Ganassi/Chevy 216.857 8. Mikhail Aleshin Schmidt/Honda 216.726 9. Ryan Hunter-Reay Andretti/Honda 216.305 10. Graham Rahal Rahal/Honda 216.299 11. James Hinchcliffe Andretti/Honda 215.898 12. Ryan Briscoe Ganassi/Chevy 215.878 13. Simon Pagenaud Schmidt/Honda 215.752 14. Ed Carpenter Carpenter/Chevy 215.326 15. Sebastien Bourdais KV/Chevy 214.713 16. Justin Wilson Coyne/Honda 214.486 17. Jack Hawksworth Herta/Honda 214.173 18. Marco Andretti Andretti/Honda 214.109 19. Carlos Munoz Andretti/Honda 213.991 20. Sebastian Saavedra KV/Chevy 213.981 21. Will Power Penske/Chevy 212.604 22. Carlos Huertas Coyne/Honda 202.319 All drivers use Dallara chassis Grid set by average speed in mph over two-lap run