Scott McLaughlin set the fastest time in the opening practice session, ahead of Colton Herta and Alex Palou at Laguna Seca.
The session was disrupted by multiple red flags and multiple drivers making mistakes early in the weekend.
After a quiet opening few minutes at Laguna Seca, Linus Lundqvist set the first lap time of first practice with a 1:11.8747.
Arrow McLaren’s new recruit, Nolan Siegel, joined the circuit to gather valuable track time in the No. 6 car.
Lundqvist raised the bar with just over an hour to go, driving to a 1:09.2218, utilising his extra set of Primary tyres for being a rookie.
Christian Lundgaard went beyond the limits of his Rahal Letterman Lanigan at the Corkscrew, running into the gravel before rejoining the circuit.
The Danish driver was in second place 20 minutes into the session before being usurped by Graham Rahal, who was sporting a striking Mobil 1 livery.
On his return to IndyCar after missing Road America, Agustin Canapino spun at Turn 6 after touching the gravel. The Argentinian managed to continue after he avoided stalling the No. 78 car.
David Malukas enjoyed an encouraging start to the session after returning from his wrist injury before spinning and stalling at Turn 1.
The marshalls quickly restarted the Meyer Shank Racing driver, and the session resumed with Malukas in 10th place.
A flurry of cars improved at Laguna Seca as the session progressed. Reigning IndyCar champion Palou moved to the top ahead of Kyle Kirkwood and Romain Grosjean.
Siegel sat in 23rd place and saved a slide as he dropped down the Corkscrew on his first visit to Laguna Seca in IndyCar.
The Corkscrew caused more problems for Santino Ferrucci, who spun and got back on track with a clever piece of car control.
Canapino made an error at Turn 8 and recovered back to the pit lane for Juncos Hollinger Racing.
The red flags were deployed for a second time after Pato O’Ward got stuck in the gravel at Turn 5; critically, the Mexican avoided the wall and damage to his Arrow McLaren with 25 minutes to go.
The session resumed a few minutes later, and Herta quickly joined the circuit for Andretti on the Firestone Primary tyre.
Marcus Ericsson switched to the gripper Alternate tyre and moved to the top of the timesheets for Andretti with a 1:08.1763 ahead of Kirkwood and Palou.
Team Penske’s Josef Newgarden bettered the Swede’s time with 13 minutes to go as Rinus Veekay moved up to third place.
Herta, a two-time winner at Laguna Seca, went fractionally faster than Newgarden within the final 10 minutes of the session.
In the closing stages, New Zealander McLaughlin went quicker than Herta to top the session, with Palou in third place.
6-time champion could only manage P18.
