NOTES: Helio Castroneves posted the fastest time in Saturday morning's qualifying session, but he didn't win the pole because he was penalized for not reducing his speed during a local caution area.
Graham Rahal had such a comfortable cushion while cruising toward victory at the Detroit Grand Prix he toyed with his push-to-pass system.
While Castroneves' second best time in qualifying was still good enough for P2 on the grid, the deletion meant that pole was handed to Rahal and the Rahal Letterman Lanigan Racing team.
Rahal became the seventh IndyCar driver to win in the first seven races of the year.
Schmidt Peterson Motorsports driver James Hinchcliffe recovered from a spin on the opening lap to go off strategy and finish third in the No. 5 Arrow Honda.
Indianapolis 500 victor Takuma Sato continued his recent good form to qualify third for Andretti Autosport ahead of team-mate Alexander Rossi, while James Hinchcliffe will start fifth on the grid alongside Scott Dixon.
There hasn't been a repeat victor in the first seven races of the season.
It was a satisfying result for Dixon after his spectacular crash in the Indy 500 in Indianapolis last week.
"Team Penske's Josef Newgarden finished fourth and Alexander Rossi of Andretti Herta Autosport with Curb-Agajanian placed fifth, putting five different teams among the top five finishers for the first time in a race this season".
IndyCar will conclude its only doubleheader of races Sunday on Belle Isle.
For Dixon, he will now be resting the ankle and preparing himself for more of the same on Sunday for race two, although he hopes to improve the performance of his auto to be in with a better shot of victory. "But she seems to be OK". "It's hard. Obviously when you have it, you don't want to miss opportunities, but hopefully the weather holds up and we can do it again". Following that race, the series will shift to Texas Motor Speedway for a race under the lights on June 10.