Simon Pagenaud claimed his second consecutive IndyCar pole position, as Penske dominated qualifying at Iowa Speedway.
Pagenaud set a two-lap average speed of 180.073mph - the only driver to crack the 180mph mark - and a cumulative time of 35.745 seconds, beating team-mate Will Power by 0.5mph and 0.4s.
Josef Newgarden, who was the last driver to take to the track during the session, was the third fastest, beating Takuma Sato - the only non-Penske driver to break under 18s over a single lap.
James Hinchcliffe finished fifth fastest after initially bumping his usurping Arrow Schmidt Peterson team-mate Marcus Ericsson from what was at that point the top spot.
Former Formula 1 driver Ericsson had been one of the few drivers to set a fast time on his first go around the track and he topped the timesheets for much of the session before eventually winding up in 10th.
Championship contender Alexander Rossi, plus Graham Rahal, Scott Dixon, and Ryan Hunter-Reay, took positions sixth to ninth.
Colton Herta will start Saturday's race in 11th place.
The race-winning 2019 rookie was the ninth driver to hit the track and set what was the second fastest time, but struggled with the same track surface issue that faced many of the early runners.
Before the session began, an ARCA support race a car had leaked oil onto the track, and the substance put down to clear the mess meant the drivers taking to the track first struggled for grip.
But there were a few high-profile drivers caught out by the issue event at the midway point, with Felix Rosenqvist qualifying 15th as a result, well adrift of his Chip Ganassi Racing team-mate Dixon.
Four-time Champ Car champion Sebastien Bourdais, who was running just before Rosenqvist, ended up 21st out of the 22 drivers.
Matheus Leist ended up last and well of the pace after a cautious run early in the session.
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