IndyCar points leader Alexander Rossi dominated a wet qualifying session in Detroit to seize the Andretti Autosport driver's second pole position of the 2018 season.
The session was split into two halves in a format unique to Detroit, with the fastest group filling the odd-numbered grid slots and, on a drying track, the second group had the advantage.
Using Firestone's brand new wet tyres, Rossi was the early pacesetter.
He topped the timesheet with his first run and was never dislodged from top spot, despite his rivals gradually reducing his advantage.
He was the only driver in the second group to outpace Schmidt Peterson Motorsports' Robert Wickens, who set the fastest group one time. As a result, Wickens joins Rossi on the front row.
Group two runners lost over three minutes at the end of the session after reigning series champion Josef Newgarden understeered into the barriers at Turn 11.
The subsequent red flag brought the session to a premature end. He will start from 19th.
Just prior to the red flag, Newgarden's Penske team-mate Will Power had climbed to second place in the group.
The Indianapolis 500 winner will start third on the grid ahead of Chip Ganassi Racing's Ed Jones.
Jones had briefly topped the timesheet in the first group before Wickens lowered the benchmark further. Eleventh place was Jones's previous best qualifying performance of the season.
Saturday's race winner Scott Dixon will line up in fifth place, with James Hinchcliffe in sixth.
Rookie Zach Veach beat his previous best qualifying effort and will start from seventh alongside 2016 series champion Simon Pagenaud, who was one of only two Chevrolet-powered cars to qualify in the top eight.
Graham Rahal, who crashed in the opening race of the weekend, ended up ninth.
Andretti Autosport's Ryan Hunter-Reay struggled in the wet conditions - he locked up at the heavy braking zone of Turn 3 on his first run of the session, before spinning on his penultimate lap.
This spin and subsequent yellow flag caused his to lose his fastest lap time and as a result, he will start from 10th place.
Santino Ferrucci, who is having his debut IndyCar weekend with a one-off appearance in Detroit, qualified his Dale Coyne Racing-prepared car in 13th.
He out-qualified team-mate Sebastien Bourdais. He will start from 16th, losing his final lap after a lock-up at Turn 7 sent him down the escape road.
Tony Kanaan, who spun on his out-lap and damaged his front wing, failed to post a time in the 12-minute session and will subsequently start 22nd.
Rene Binder also failed to post a time and will start last.
|1||Alexander Rossi||Andretti Autosport||Dallara/Honda||1m33.3143s|
|2||Robert Wickens||Schmidt Peterson Motorsports||Dallara/Honda||0.3462s|
|3||Will Power||Team Penske||Dallara/Chevrolet||0.5152s|
|4||Ed Jones||Chip Ganassi Racing||Dallara/Honda||0.6113s|
|5||Scott Dixon||Chip Ganassi Racing||Dallara/Honda||0.6401s|
|6||James Hinchcliffe||Schmidt Peterson Motorsports||Dallara/Honda||0.8227s|
|7||Zach Veach||Andretti Autosport||Dallara/Honda||1.3321s|
|8||Simon Pagenaud||Team Penske||Dallara/Chevrolet||0.9172s|
|9||Graham Rahal||Rahal Letterman Lanigan||Dallara/Honda||1.7113s|
|10||Ryan Hunter-Reay||Andretti Autosport||Dallara/Honda||1.1878s|
|11||Jordan King||Ed Carpenter Racing||Dallara/Chevrolet||1.8231s|
|12||Marco Andretti||Andretti Herta||Dallara/Honda||1.2332s|
|13||Santino Ferrucci||Dale Coyne Racing||Dallara/Honda||2.1521s|
|14||Gabby Chaves||Harding Racing||Dallara/Chevrolet||2.2902s|
|15||Spencer Pigot||Ed Carpenter Racing||Dallara/Chevrolet||3.0570s|
|16||Sebastien Bourdais||Dale Coyne Racing||Dallara/Honda||2.3549s|
|18||Matheus Leist||AJ Foyt Enterprises||Dallara/Chevrolet||2.7296s|
|19||Josef Newgarden||Team Penske||Dallara/Chevrolet||4.9898s|
|20||Takuma Sato||Rahal Letterman Lanigan||Dallara/Honda||3.7708s|
|22||Tony Kanaan||AJ Foyt Enterprises||Dallara/Chevrolet||-|
|23||Rene Binder||Juncos Racing||Dallara/Chevrolet||-|