Power lapped the 2.5-mile Indianapolis Motor Speedway oval in 39.2633s, a speed of 229.222mph, with the benefit of a huge tow in his Chevrolet-powered car.
But the session was marred by a serious crash at Turn 1 between Katherine Legge and Stefan Wilson, which caused the latter to be hospitalised for advanced imaging and further evaluation.
With qualifying done and dusted, this session was all about race preparation and drafting practice in traffic. The cars’ engines were returned to 1.3-bar turbo boost – race boost levels – for the two-hour session that began at 1pm local time.
Chip Ganassi Racing’s Scott Dixon set the early pace at 229.184mph after six minutes, ahead of polewinning team-mate Alex Palou (227.392mph), both assisted by a big tow from a group of cars ahead.
Dixon’s car then headed back to Gasoline Alley for a set-up change, while Palou also took time out to “work on a couple of things”.
All teams were allowed to pit off Turn 4, rather than Turn 3, as they will in the race and Colton Herta (Andretti Autosport) had a near-miss with Benjamin Pedersen’s dawdling AJ Foyt Racing car early on.
After a yellow for a track inspection, Pedersen jumped up to fourth with 226.302mph having been slowest after the opening hour.
The first crash of the entire week of practice and qualifying occurred with 50 minutes remaining, when Legge (Rahal Letterman Lanigan Racing) and Wilson (Dreyer & Reinbold) collided at Turn 1, just after Santino Ferrucci (AJ Foyt Racing) had passed Devlin DeFrancesco (Andretti Autosport) on the front stretch.
Legge’s left-front wheel ran into the right-rear corner of Wilson as he checked up. The contact caused both cars to spin before they struck the wall, with Legge’s car hitting side-on as Wilson’s went nose-first into the SAFER barrier.
Legge’s car, which suffered severe right-side damage, briefly got airborne before landing on its belly and impacting the wall again at Turn 2.
Legge climbed out of her car, but the AMR safety crew took 10 minutes to extract Wilson from his car, and as he was stretchered to the ambulance he raised his thumb to the crowd.
“The cars in front were all checking up, I lifted as much as I could and downshifted, hit the brakes but it wasn’t enough as they were checking up,” said Legge.
“I got into the back of Stefan and we both ended up in the wall.”
The session resumed for 30 minutes, Power heading to the top of the charts with 229.222mph with 25 minutes remaining.
Takuma Sato (Ganassi) moved into third, behind Dixon, at 228.382mph as Palou fell to fourth.
Arrow McLaren’s Tony Kanaan and ECR’s Conor Daly rounded out the top six while Marco Andretti (Andretti Autosport) was seventh quickest from Pedersen, Pato O’Ward (McLaren) and Herta.
Practice resumes on Friday at 11am, local time, for the two-hour Carb Day practice – the last on-track action before the start of the Indy 500 on Sunday.