Russell, who completed 76 laps, led McLaren’s Oscar Piastri by just 0.010s at the Sakhir venue.

Charles Leclerc put Ferrari third and 0.280s away from the Silver Arrows while McLaren’s Lando Norris was fourth and half a second back as he battled braking issues.

Collectively, McLaren completed 124 laps with 54 for Norris and 70 for Piastri.

The Woking-based team said it spent the day working on various setups on various tyre compounds in various temperatures.

“Overall, it has been a productive day,” said Piastri.

“My running in the afternoon felt solid and we made good progress. The conditions were different today to last week, with some warmer temperatures in my session combined with different wind conditions, so it was good to be able get that experience in the car.

“I am feeling more comfortable with each lap, so am looking forward to getting back out on track tomorrow afternoon.”

Norris added: “We got some good laps under our belts this morning, working though varying runs and getting more comfortable in the car.

“Conditions today were a bit different to last week, with the changing wind as well as the slightly cooler temperatures this morning compared to this afternoon, giving us a little bit more grip.

“We’re learning more each day, but there are still a lot of things to get our heads around, so we’ll keep putting the car through its paces in the last two days of testing.”

Max Verstappen was the only driver not to get on track, with Red Bull electing to give Isack Hadjar the full day’s running.

The morning session ran without any major incident, though the same couldn’t be said for the afternoon session.

Aston Martin’s Lance Stroll brought out the red flag when he beached his AMR26 in the gravel trap at Turn 11.

That wasn’t the only issue for Aston Martin. Fernando Alonso was limited to just 28 laps with power unit trouble. Stroll, meanwhile, cut just 26 laps.

“A few issues kept us in the garage at times today and we are still missing all-important mileage with this car,” said Aston Martin chief trackside operator Mike Krack.

“The priority for the remaining days is to get laps under our belt.

“Despite the lack of running, we are learning huge amounts with every lap and we are taking steps forward with how to operate the car under these new regulations.

“We know where to focus and every area of the team is fully focussed on improving our competitiveness.”

Testing at Bahrain will continue on Thursday at 6pm AEDT.

Results: Formula 1 Bahrain Pre-Season Test Day 1