All three were in the second group under IndyCar’s new-for-2024 split practice format, with Rosenqvist setting a 1:00.3390s in the final segment of the afternoon in the #60 Honda.

It was a time which proved almost half a second faster than McLaren’s O’Ward and Chip Ganassi Racing’s Armstrong could manage, with Team Penske’s Will Power fourth, and fastest of those from the odd-numbered group around the Streets of St Petersburg.

Despite the new group format for Practice 1, there were still just a handful of cars on-track in the opening minutes, with Christian Rasmussen setting the early pace in the #20 Ed Carpenter Racing Chevrolet.

He was down to a 1:02.6235s before Marcus Ericsson clocked back-to-back 1:02.5305s and 1:02.1361s in the #28 Andretti Autosport Honda.

So followed a flurry of changes at the top of the timing screen, with Rosenqvist quickest once the opening, 20-minute segment came to a close with a 1:01.0557s.

Power (#12 Chevrolet) had just moved to second on a 1:01.2630s when a red flag was called, three minutes into the first segment for the drivers in odd-numbered pit boxes, in response to Kyffin Simpson stopping in the Turn 10 run-off in the #4 CGR Honda.

Minutes later, Pietro Fittipaldi caused another when the #30 Rahal Letterman Lanigan Racing Honda ended up stuck in the same spot as Simpson had, with the segment not restarting.

Those in even-numbered pit boxes then rolled out for 10 minutes of running, during which Colton Herta shifted the benchmark to a 1:00.9937s in the #26 Andretti Global w/ Curb-Agajanian Honda.

The odds came back out and, halfway into that segment, Scott McLaughlin clocked a 1:00.9106s in the #3 Penske Chevrolet, before Rinus VeeKay usurped him next time around with a 1:00.8848s in the #21 ECR Chevrolet.

Power reset the fastest lap with a 1:00.8409s and that was still the benchmark at the end of the segment.

Halfway into the final, 10-minute stanza of the morning, though, Armstrong bettered that with a 1:00.8182s and then Rosenqvist set the 1:00.3390s moments later.

Santino Ferrucci triggered a red flag when he drove the #14 AJ Foyt Racing Chevrolet up the run-off area at Turn 10 inside the final three minutes, but the session restarted.

The chequered flag had come out by the time O’Ward set his 1:00.8112s in the #5 Chevrolet, 0.4722s slower than Rosenqvist’s best.

Fifth all-told went to VeeKay, from McLaughlin, Romain Grosjean, Herta, 2023 champion Alex Palou, and McLaren injury replacement Callum Ilott.

Practice 2 starts on Saturday at 09:35 ET/Sunday at 01:35 AEDT and then Qualifying from 14:00 ET/06:00 AEDT.

Results: Practice 1