Palou set a 1:01.7210s when the field switched to ‘green’ alternate compound tyres after Andretti Global’s Colton Herta achieved a benchmark of 1:02.0219s on the ‘black’ primaries.

The day’s sole practice session began with an all-in, 45-minute segment before the field was split in two for 10 minutes of track time each.

Christian Lundgaard (#45 Rahal Letterman Lanigan Racing Honda) was among the early pace-setters with a 1:10.6067s on this third lap, before Scott McLaughlin (#3 Team Penske Chevrolet) set a 1:04.8342s.

Lundgaard hit back almost immediately with a 1:03.6125s before Herta (#26 Honda) set a 1:03.0957s and then Palou (#10 Honda) a 1:02.9507s.

McLaughlin was back on top with a 1:02.9582s before Palou punched out 1:02.7776s and 1:02.6929s on his eighth and 10th laps.

Herta reclaimed the ascendancy with a 1:02.0973s and later moved the benchmark to a 1:02.0219s in the 35th minute of proceedings, which remained the fastest lap of the opening segment.

When the chequered flag came, Will Power (#12 Team Penske Chevrolet) was second on a 1:02.4474s and McLaughlin third on a 1:02.4845s.

Group 1 and rookies were then released for 10 minutes of running, with most taking the opportunity to head out immediately on a set of ‘green’ alternate tyres.

Proceedings were interrupted early when Christian Rasmussen (#20 Ed Carpenter Racing Chevrolet) ran up a run-off area and stalled.

There was finally movement near the top in the last two minutes when McLaughlin – who had been into run-offs multiple times – went to second on a 1:02.2739s before Palou reclaimed top spot with a 1:01.7210s.

Kyle Kirkwood had sat out much of the first segment and also incurred contact when Josef Newgarden (#2 Penske Chevrolet) tried to squeeze his way through a traffic jam.

However, just prior to the chequered flag in Group 1, he was able to jump to second place with a 1:01.8103s on a green-shod #27 Andretti Honda.

Pato O’Ward set the pace when Group 2 headed out, with a 1:01.7315s in his #5 McLaren Chevrolet which left the Mexican second overall, ahead of Herta on a 1:01.7968s and then Kirkwood.

Rounding out the top 10 were McLaughlin, Newgarden, Santino Ferrucci (#14 AJ Foyt Racing Chevrolet), Marcus Armstrong (#11 CGR Honda), Power, and Lundgaard.

Practice 2 starts on Saturday at 09:10 ET/23:10 AEST and then Qualifying from 12:15 ET/Sunday at 02:15 AEST.

Results: Practice 1