Defending IndyCar Series champion Will Power has aced qualifying to clinch an all-important pole position for the Go Pro Grand Prix of Sonoma.

In a clinical exhibition, Power dominated qualifying to give himself the best possible chance of retaining the Astor Cup.

Power claimed his sixth pole position of the year and a valuable bonus point with a blistering record tour of 1:16.25s in the dying stages of the 10-minute Fast Six final phase of qualifying.

CHF Racing driver Josef Newgarden, who remains a mathematical chance at the title with double points on offer, had gone to the top but his effort fell .13s short.

Power said:”I’m really stoked. I love qualifying and very happy to end the year with a pole position.

“(there are)Lots of points on the table; we’ll go for that win.”

Andretti Autosport’s Ryan Hunter-Reay saw his best lap of 1:16.52s good enough to claim third ahead of Team Penske’s Simon Pagenaud however the two drivers are both out of series contention.

Series leader Juan Montoya will start fifth as the nearest to the Colombian in the points, Graham Rahal starts beside him in sixth.

After turning a total of four laps in Group 2, Scott Dixon (third in the points standings) missed a place in the top six with the Ganassi driver to start from ninth.

Not so lucky was Helio Castroneves, the only one of the six series contenders to fail to advance from Round 1.

Castroneves will start from 15th position with Team Penske likely to enforce a Plan B strategy into action.

Full qualifying results

Points standings