Ryan Briscoe helped his Penske teammate Helio Castroneves' chances of winning the IRL IndyCar Series title by beating points leader Scott Dixon to pole position for the championship decider at Chicagoland.
Ganassi driver Dixon, who had dominated practice, held provisional pole for most of the session, resisting strong challenges from the Andretti Green cars in particular.
But Briscoe, the last driver to take to the track, set a four lap average of 215.818mph to snatch pole away from Dixon, out-pacing the Kiwi by just over a tenth of a second.
Castroneves had to settle for fourth, behind AGR's Danica Patrick, following his qualifying effort, although there was further controversy after television replays suggested that the Brazilian had dipped below the white line separating the race track from the apron during his lap - an action that some in the pitlane felt should incur a penalty.
Andretti Green's Tony Kanaan and Marco Andretti will share row three, ahead of Dixon's Ganassi teammate Dan Wheldon and Luczo Dragon Racing's Tomas Scheckter.
Vitor Meira, who could be making his final start for Panther Racing if Wheldon takes his drive as early as the Surfers Paradise non-championship race, qualified ninth, with the much-maligned Marty Roth again showing better oval form to take 10th on the grid.
Detroit winner Justin Wilson (Newman/Haas/Lanigan) struggled on the 1.5-mile oval and only qualified 22nd.
Pos Driver Team Speed
1. Ryan Briscoe Penske 215.818
2. Scott Dixon Ganassi 215.553
3. Danica Patrick Andretti Green 215.548
4. Helio Castroneves Penske 215.372
5. Tony Kanaan Andretti Green 215.368
6. Marco Andretti Andretti Green 215.064
7. Dan Wheldon Ganassi 214.967
8. Tomas Scheckter Luczo Dragon 214.855
9. Vitor Meira Panther 214.796
10. Marty Roth Roth 214.794
11. Will Power KV 214.583
12. Hideki Mutoh Andretti Green 214.444
13. Oriol Servia KV 214.441
14. Ed Carpenter Vision 213.875
15. Graham Rahal Newman/Haas/Lanigan 213.523
16. AJ Foyt IV Vision 213.485
17. Ryan Hunter-Reay Rahal Letterman 213.430
18. Jaime Camara Conquest 213.417
19. Sarah Fisher Sarah Fisher 213.389
20. Alex Tagliani Conquest 213.305
21. Milka Duno Dreyer & Reinbold 212.857
22. Justin Wilson Newman/Haas/Lanigan 212.753
23. Buddy Rice Dreyer & Reinbold 212.682
24. Darren Manning Foyt 212.406
25. Franck Perera Foyt 212.126
26. Bruno Junqueira Dale Coyne 212.040
27. EJ Viso HVM 211.996
28. Mario Moraes Dale Coyne 211.451