Andretti Autosport’s Colton Herta has set the fastest lap in each session on the opening day of IndyCar’s pre-season Open Test at The Thermal Club.

The Californian was the only driver to break into the 1:39s in the first session, when he set a 1:39.9303s, before going as quick as a 1:39.3721s in the second session.

“Just a lot of knocking the rust off,” said Herta.

“It’s really good to get the team back into it, get all the boys working again and just get everybody back into the flow.

“It’s nice to be back in a car. It’s a fun track to drive.”

Christian Lundgaard ended up just 0.0046s in arrears despite losing five minutes of track time in the three-hour hit-out when he spun his Rahal Letterman Lanigan Racing entry to cause a red flag.

Chip Ganassi Racing’s Alex Palou took third while Andretti’s Romain Grosjean made for an all-Honda top four.

First of the Chevrolet-powered drivers was Team Penske’s Will Power in fifth on a 1:39.5690s, the 2022 champion still driving Car #12.

Rounding out the top 10 were Scott Dixon (Ganassi), Callum Ilott (Juncos Hollinger Racing), Scott McLaughlin (Penske), Simon Pagenaud (Meyer Shank Racing), and rookie Marcus Armstrong (Ganassi), with the top 13 all getting into the 1:39s in Practice 2.

Action resumes tomorrow at 09:00 local time/04:00 AEDT.

CLICK HERE for an onboard lap from IndyCar’s first day at The Thermal Club

Results: Day 1