Graham Rahal topped the opening practice session ahead for the Gallagher Grand Prix for Rahal Letterman Lanigan ahead of Arrow McLaren’s Felix Rosenqvist.
Christian Lundgaard set the third quickest time in a competitive session for RLL, as just half a second separated the top 10.
The opening practice session at Indianapolis got underway, and many cars joined the track for an installation lap.
In a doubleheader weekend with the NASCAR Cup Series, the 90-minute session remained quiet in the first few minutes.
Sting Ray Robb set the first competitive time of the session, driving to a 1:12.1311 before improving to a 1:11.76533 with 15 minutes gone.
Benjamin Pedersen sat second on the timesheets, caught a snap of oversteer at Turn 2 and managed to continue on the circuit.
Juncos Hollinger Racing’s Agustin Canapino’s 1:11.5654 was good enough to usurp Robb atop the timesheets, as Marcus Armstrong slotted into second place.
Linus Lundqvist performed admirably last time out in Nashville and found himself fifth fastest at IMS with an hour left.
The times continued to tumble as Lundgaard broke the 1:11 barrier, achieving a 1:10.4945 ahead of Armstrong.
Arrow McLaren’s Rosenqvist sat in third place; the Swede is looking to bounce back after a disappointing weekend last time out in Tennessee.
Pedersen’s eventful day it was continued as the 24-year-old locked up at Turn 12 and drove across the grass.
Alex Rossi set the quickest time, going quicker than Lundgaard with a 1:10.3981 for Arrow McLaren, on his return to the venue of his sole podium so far this season.
The American’s time was quickly beaten by the championship leader Palou who went fractionally quicker as the track continued to grip up.
The track remained relatively quiet with 45 minutes to go; the Indy 500 winner Josef Newgarden improved to P18 after besting his teammate Scott McLaughlin’s effort.
Lundqvist suffered from mechanical trouble, which stopped him from gaining valuable track time, and the Swede languished down in P24.
The first red flag of the session was introduced after Pato O’Ward spun after dipping his right side tyre on the grass and stalling his Chevrolet engine.
The AMR Safety Team restarted the Arrow McLaren, and the green flags were deployed with 38 minutes to go.
Palou continued to hold the fastest time with half an hour remaining, ahead of Rossi and Lundgaard.
Rahal broke into the top five going fractionally quicker than the number 26 car, just over an hour into the session.
Herta locked his right front tyre into Turn 1 and rejoined through the escape road without damaging his Dallara chassis.
Extra tyre stacks were placed in the runoff area in an attempt to slow the cars down before they rejoin the circuit.
British driver Callum Ilott had a quiet session in the number 77 car, having set just 10 laps with 20 minutes to go.
The softer Alternate tyres made their debut in the session as Rosenqvist set the best time of 1:09.9267 for Arrow McLaren.
Rahal got in front of the Swede in the closing stages, driving to a 1:09.8421 with eight minutes to go. Lundgaard sat in third place in a very impressive session for RLL.
David Malukas locked up and ran wide at Turn 7 in the final minute of practice but continued without damaging his car.
