Rosenqvist set the fastest four-lap average of 233.947mph around the 2.5-mile oval with just over an hour remaining of the six-hour session, boasting a quickest single lap 234.329mph.
“That was a phenomenal run,” he said. “I wasn’t super-happy with my first run, so we trimmed the car out but I had no idea we’d be so quick. That put a smile on my face.”
Alexander Rossi made it a McLaren 1-2, taking full advantage of a favorably-early draw inside the opening 40 minutes to set an average of 233.528mph, with a fastest single-lap of 234.177mph.
Chip Ganassi Racing’s Alex Palou was third quickest with 233.528mph, which he set in much warmer track temperatures in the second hour of the session, following an overnight Honda engine change.
Rinus VeeKay (Ed Carpenter Racing) was fourth, ahead of Scott Dixon (CGR) who enjoyed his best run at the warmest part of the day, and was also forced to change his engine overnight.
Tony Kanaan, who starts his final race next weekend, rolled back the years with a 233.347mph effort to make it three McLarens in the top six.
Also making the Fast 12 were Takuma Sato (CGR), Pato O’Ward (McLaren), Santino Ferrucci (AJ Foyt Racing), Marcus Ericsson (CGR), top rookie Benjamin Pedersen (Foyt) and Will Power (Team Penske).
Source: Autosport