Power set the only 182mph opening lap with a 182.366 and his second lap was a 183.089 – an average of 182.727mph - which landed the Penske driver his fourth pole position of the season and the 67th of his career.
Rookie Devlin DeFrancesco clocked a 179.531mph average for Andretti Steinbrenner Autosport to sit top after the first seven cars had run, continuing his fine work from the practice session and last week’s rookie test.
Takuma Sato of Dale Coyne Racing with RWR was next to top the times, turning a 180.476mph lap followed by a 179.623mph to give him the first average to crack the 180mph barrier, although he admitted he’d had to work hard to contain his car’s handling traits.
David Malukas, in the Coyne with HMD car, was unable to match Sato's time, nor beat fellow rookie DeFrancesco, but he delivered a solid run to claim third at the time.
Romain Grosjean, like Sato, ran a 180mph opening lap and high 179 second lap, to slot into second, although the Frenchman will have to take a nine-place grid drop due to an early fifth engine change.
While he was able to shade team-mate DeFrancesco, Colton Herta could not after having a wiggle out of Turn 3 and having to breathe the throttle.
His issues were mild compared with Felix Rosenqvist, who looped his car into a spin exiting Turn 2. But the Swede remarkably kept the Arrow McLaren SP off the outside SAFER barrier, and only gently rolled backward into the inside tyre wall. Rosenqvist, a potential polesitter, will thus start the race from the back of the 26-car grid.
Then the second AMSP car set a 179.958 followed by a 180.650, beating Sato’s average by 0.25mph with an average of 180.303mph, but his time at the top didn’t last long. The very next car out, Scott McLaughlin (Penske) delivered two 181mph laps resulting in an average of 181.406mph.
Next out was Alex Palou, and his Chip Ganassi Racing also set two 181mph laps to claim second, but then Josef Newgarden in the #2 Penske was 180.747mph on the first lap – with a self confessed ‘goof’ downchange at Turn 3 – but then ran a remarkable 182.520mph on his second lap.
The second practice session will start 45 minutes early for nine cars who will attempt to clean and lay rubber on the higher line. All 26 cars will be on track from 6.45pm CT (00.45am UK time).