Iowa IndyCar: Penske's Helio Castroneves takes pole position

Castroneves was 18th in line to make his qualifying run, and reeled off a two-lap average of 183.480mph to defeat the 183.125mph effort set a few minutes earlier by Kanaan.

"The conditions changed a little bit," said Castroneves.

"Obviously the heat is the biggest factor, and we as a team [Penske] were able to find a good balance.

"The car was strong last week in Milwaukee, it's showing that it's very strong here as well, and I can't wait to start the race now."

While the temperature was certainly a factor, it was actually fractionally cooler than during Friday practice, although the heat index was still in the low-30s with a track temperature of around 55C.

Points leader Juan Pablo Montoya will start from third on the grid; a satisfying result for a driver who said that he hadn't placed a huge premium on qualifying.

"I just figured that anything in the top five would be OK," he surmised.

Scott Dixon, Simon Pagenaud and Will Power rounded out the top six for a Penske/Ganassi lockout of the first three rows, while Marco Andretti took the honours for fastest Honda in eighth, where he will start alongside team-mate and last year's winner Ryan Hunter-Reay.

Last weekend's winner Sebastien Bourdais failed to set a time after the rear of his car snapped out and spun him up the track.

It was only a remarkable save from the Frenchman that kept the car from suffering anything more than a glancing blow against the outside wall.

QUALIFYING RESULTS: