Scott McLaughlin headed a chaotic opening practice session of the weekend at the Children's of Alabama Indy Grand Prix.
First practice at Barber Motorsports Park was interrupted on three occasions by red flags as Helio Castroneves, Romain Grosjean and Will Power all found themselves in strife.
After a slow start to the session, McLaughlin registered a late 1:06.6610s effort to top the order by 0.1583s from Colton Herta, with Power and Scott Dixon completing the top four.
Early championship leader Marcus Ericsson was fifth with a 1:06.9994s.
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The 75-minute session got off to a slow start with rookie drivers Sting Ray Robb, Agustin Canapino, Benjamin Pedersen and Marcus Armstrong making use of their extra set of tyres over the more experienced runners.
This is the first track that Armstrong has previous experience of, a fact that showed on an early push lap when the New Zealander got the tail of his Chip Ganassi Racing Honda loose on the exit of Turn 7 with 15 minutes gone.
As the clock ticked down to show 53 minutes remaining, Armstrong topped the order with a time of 1:07.7542s.
Castroneves caused the first red flag of the session after 20 minutes after bouncing across the harsh Turn 9 kerbs, skating across the gravel and making heavy contact with the wall.
Remarkably, the #06 Meyer Shank Racing driver was able to recover back to the pits and continue after his nosecone was changed.
Shortly after the restart, Colton Herta came close to repeating Castroneves' incident in his Andretti Autosport Honda but backed out and opened his steering before striking the concrete kerbing.
The session was then paused for a second time after Andretti Autosport instructed Grosjean to stop his Honda with smoke billowing from the right-hand side of his Honda engine.
With half an hour remaining, 2021 Barber Motorsports Park race-winner Alex Palou led the way with his 1:07.3779s. McLaughlin footed the times at this stage after completing just two laps.
This was rectified shortly after the track returned to green flag conditions, however, as the #3 driver leapt to third.
The lead changed in the 55th minute as Dixon displaced Palou by 0.1108s as early championship leader Ericsson also positioned himself in the top three.
Pato O'Ward caused a sharp intake of breath to be taken on the Arrow McLaren gantry with 15 minutes remaining as he got it all crossed up on the entry to Turn 13, hopping across the grass and wiping out several advertising boards as he recovered.
I was on my first lap. Just letting them know it was ok https://t.co/5zjtuCMyU3
— Scott McLaughlin (@smclaughlin93) April 28, 2023
Not so lucky was Power, who collided with the wall at Turn 2 moments after fitting the alternate compound Firestone tyres. On the exit of Turn 1, the Australian clipped the dirt and was then powerless to prevent his Team Penske Chevrolet from making the short trip across the gravel and causing a third red flag interruption.
Only six drivers had completed timed efforts on the alternate compound when the session was paused for the final time, which caused significant traffic problems in the closing minutes.
As the final laps were registered, Lundgaard, Ericsson and Herta all took turns at the top before McLaughlin registered a hammer blow to end the running 0.1583s clear of the chasing pack.
Practice 2 starts on Saturday at 12:00 ET/Sunday at 02:00 AEDT and then Qualifying from 15:00 ET/05:00 AEDT.