Pagenaud lapped the 0.894-mile oval Iowa Speedway in 17.8479 and 17.8976sec (180.324 and 179.823mph respectively) to beat Power’s two-lap average by 0.0963sec and claim his second pole position at the venue.

Newgarden’s first lap was quicker than Power’s first, but his second dropped the championship leader to third. He’ll be joined on the second row by Takuma Sato in the Rahal Letterman Lanigan Racing-Honda.

Arrow Schmidt Peterson Motorsports-Honda produced its best qualifying performance of the season, defending Iowa winner James Hinchcliffe clocking fifth-fastest with Marcus Ericsson top rookie with 10th-fastest.

In between them lie Alexander Rossi (Andretti Autosport-Honda), Graham Rahal in the second RLLR machine, Scott Dixon (Chip Ganassi Racing-Honda) who has yet to win at this track and Ryan Hunter-Reay (Andretti) who has three Iowa wins to his name.

Rookies Colton Herta (Harding Steinbrenner Racing) and Santino Ferrucci (Dale Coyne Racing) will occupy the sixth row, just ahead of 2010 Iowa winner Tony Kanaan, who gave AJ Foyt Racing-Chevrolet its most promising quali run of the season.

Sage Karam, making his second start for Carlin Racing-Chevy and his third of the season, was an impressive 14th-fastest.

Final practice will commence at 6pm local (Central) time, an hour long session devised to give teams and drivers a chance to simulate raceday running.

Session results: