Rosenqvist set the fastest four-lap average of 234.081mph around the 2.5-mile oval, boasting a quickest single lap 234.534mph.
With the track temperature up 20-degrees since final practice, speeds were slightly slower as the cars required more downforce on the warmer racing surface. But light winds helped the drivers to stay flatout on the throttle.
Ferrucci unleashed a stellar four-lap run of 233.911mph that set the pace for much of the session in his Chevrolet-powered Foyt machine.
“That’s about as close to the wall as I’ve ever been in qualifying here,” said Ferrucci. “Definitely the fastest four laps of my life. I want to make history and I want that pole.”
But Rosenqvist virtually matched Ferrucci’s first and second lap speeds and dropped off less on his third and fourth tours to go to the top with 234.081mph, beating Ferrucci by two tenths of a second over the four laps.
“It really helped to see my team-mates run and they gave me good feedback,” said Rosenqvist. “We actually bettered our run from yesterday when it was hotter. Let’s go and do it again.”
Rinus VeeKay (Ed Carpenter Racing), who suffered an exhaust header problem in final practice, almost matched Ferrucci’s pace lap by lap to produce 233.801mph, which was good for third.
He said: “Very happy, it was tough this morning with the issues, but the crew brought their A-game and the engine felt great. Pretty happy with that.”
Santino Ferrucci, A.J. Foyt Enterprises Chevrolet
Photo by: Michael L. Levitt / Motorsport Images
Alex Palou (Chip Ganassi Racing) set a huge 234.581mph first lap, but his pace then fell away and he dropped behind both Ferrucci and VeeKay, ending with an average of 233.779mph in fourth.
“We tried, and we saw the big speeds from Santino and VeeKay, but it’s good to get two Ganassi cars in the Fast Six,” said Palou.
He was backed up by team-mate Scott Dixon in fifth at 233.430mph.
“That was pretty on the limit on downforce and balance, the last three laps I was hanging on pretty tight as we went quite aggressive,” said Dixon. “Some cars out here seem to have a ton of speed.”
Pato O’Ward (McLaren) just made the Fast Six with 233.229mph for sixth and said: “I think we missed it there a little bit, it started getting really wiggly.”
Of those who didn’t make it to the Firestone Fast Six, Alexander Rossi (McLaren) struggled through Turn 3 on his way to 233.110mph and will start the Indy 500 in seventh. “We didn’t quite get the balance right, but seventh is a good starting spot,” he said.
Takuma Sato (CGR) will start eighth, ahead of Tony Kanaan (McLaren), Marcus Ericsson (CGR), top rookie Benjamin Pedersen (AJ Foyt Racing) and Will Power (Team Penske), the latter reporting: “We had a big push on the second lap and I had to lift and got close to the wall.”
Firestone Fast Six qualifying, that will decide the pole winner of the 107th Indy 500, takes place at 5:15pm local time.