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
Pos | Num | Driver | C/E/T | Fastest lap | Split 1st/prev | Lap |
1 | 10 | Alex Palou | D/H/F | 1:01.7210 | 31/31 | |
2 | 5 | Pato O’Ward | D/C/F | 1:01.7315 | 0.0105/0.0105 | 25/30 |
3 | 26 | Colton Herta | D/H/F | 1:01.7968 | 0.0758/0.0653 | 31/31 |
4 | 27 | Kyle Kirkwood | D/H/F | 1:01.8103 | 0.0893/0.0135 | 19/20 |
5 | 3 | Scott McLaughlin | D/C/F | 1:02.0959 | 0.3749/0.2856 | 32/33 |
6 | 2 | Josef Newgarden | D/C/F | 1:02.2377 | 0.5167/0.1418 | 31/32 |
7 | 14 | Santino Ferrucci | D/C/F | 1:02.3277 | 0.6067/0.0900 | 32/32 |
8 | 11 | Marcus Armstrong | D/H/F | 1:02.4307 | 0.7097/0.1030 | 23/30 |
9 | 12 | Will Power | D/C/F | 1:02.4474 | 0.7264/0.0167 | 16/30 |
10 | 45 | Christian Lundgaard | D/H/F | 1:02.4726 | 0.7516/0.0252 | 30/31 |
11 | 78 | Agustin Canapino | D/C/F | 1:02.5693 | 0.8483/0.0967 | 30/31 |
12 | 9 | Scott Dixon | D/H/F | 1:02.7007 | 0.9797/0.1314 | 26/26 |
13 | 15 | Graham Rahal | D/H/F | 1:02.7235 | 1.0025/0.0228 | 35/35 |
14 | 28 | Marcus Ericsson | D/H/F | 1:02.7515 | 1.0305/0.0280 | 22/34 |
15 | 7 | Alexander Rossi | D/C/F | 1:02.8537 | 1.1327/0.1022 | 30/30 |
16 | 60 | Felix Rosenqvist | D/H/F | 1:02.9030 | 1.1820/0.0493 | 30/30 |
17 | 30 | Pietro Fittipaldi | D/H/F | 1:02.9237 | 1.2027/0.0207 | 34/34 |
18 | 20 | Christian Rasmussen | D/C/F | 1:02.9473 | 1.2263/0.0236 | 38/38 |
19 | 77 | Romain Grosjean | D/C/F | 1:03.0225 | 1.3015/0.0752 | 28/29 |
20 | 6 | Theo Pourchaire | D/C/F | 1:03.1142 | 1.3932/0.0917 | 30/39 |
21 | 4 | Kyffin Simpson | D/H/F | 1:03.1501 | 1.4291/0.0359 | 42/42 |
22 | 66 | Helio Castroneves | D/H/F | 1:03.2331 | 1.5121/0.0830 | 30/30 |
23 | 21 | Rinus VeeKay | D/C/F | 1:03.3195 | 1.5985/0.0864 | 34/34 |
24 | 41 | Sting Ray Robb | D/C/F | 1:03.4996 | 1.7786/0.1801 | 14/30 |
25 | 8 | Linus Lundqvist | D/H/F | 1:03.5764 | 1.8554/0.0768 | 19/40 |
26 | 18 | Jack Harvey | D/H/F | 1:04.2658 | 2.5448/0.6894 | 11/25 |
27 | 51 | Tristan Vautier | D/H/F | 1:04.6214 | 2.9004/0.3556 | 23/34 |