Norris moves into third behind the two Ferraris, 0.218s off Leclerc's top time.
A strong second day for Sauber so far as Bottas moves up to third, 0.4s shy of Leclerc's benchmark.
A tidy lap overall from the Finn.
Another major change to the timing screen as Sainz slots into second.
Sainz is just over a tenth off teammate Leclerc, who was in action earlier today.
Bottas moves his Sauber up the order, slotting into a respectable P4.
He's 0.651s off Leclerc's top time from earlier, running on the favoured C3 tyre.
Stroll has just moved up one place and into fourth, pushing Sargeant down to fifth in the process.
The Aston Martin driver's latest effort is 0.669s off the current benchmark.
Sainz is out for the first time today, having taken over driving duties in the SF-24 from Ferrari teammate Leclerc.
He goes eighth quickest with his first timed lap of the day, 1.6s off what Leclerc managed this morning.
Hamilton has just jumped up to second in the timesheets with his best lap of the time.
It's a 1m32.273s from the seven-time world champion, putting him 0.523s off Leclerc.
Everyone out on track looks to be focused on long-running at the moment, so no major changes in the timesheets.
"I was actually standing right in front of the drain cover when it came out, because I went on track to see," he told F1TV.
"And I was looking at it like, ‘yellow flag it, yellow flag it, yellow flag it – someone’s going to take it!’ Boom, my team-mate came and took it.
"So I felt like it could have been avoided in a way, but I missed by one lap. Because I went to speak to the marshal, and just when I was speaking to him, it happened."
Norris has headed out in his McLaren for his first laps of the day, after taking over from teammate Piastri.
He is one of four drivers (the others being Leclerc, Perez and Hamilton) currently circulating on track at the moment.
Red Bull have confirmed that Perez will continue to drive for the rest of Thursday after that disrupted morning session.
The Mexican is straight to work early on, as is Ferrari's Leclerc, fresh with his new floor.
Green light and we are go for the afternoon session. We will have five hours of running after the curtailed morning
It wasn't all plain-sailing for Perez on his first day driving the RB20 in Bahrain.
After a smooth and trouble-free day for teammate Verstappen on Wednesday, the same couldn't be said for Perez, who encountered an early brake issue which confined him to the garage for over half an hour.
The Mexican completed the fewest laps of anybody (20) before the red flag cut short running this morning. Verstappen is scheduled to get back in the car for the now-extended afternoon session.
Confirmation from Ferrari that Leclerc did indeed pick up damage when he ran over the drain cover down at Turn 11. Ferrari have since changed the floor of the SF-24.
Here's the story of what happened on the second morning of F1 pre-season testing in Bahrain.
Leclerc ended up fastest before dislodging a drain cover, which caused the session to be red-flagged and ultimately curtailed early.
News from the FIA: The morning session will not be resumed due to the drain cover coming loose at Turn 11.
An F1 spokesperson says "repairs are underway and it is expected that the repair will be concluded within one hour".
As a result, the afternoon session will begin one hour earlier than planned at 11am UK time.
Here is the current scene down at Turn 11 as repair work is carried out on the loose drain cover.
While we are under the red flag, you can check out a sensational revelation from the new series of Netflix's Drive to Survive, which will be released on Friday.
During one episode, Hamilton claims he was told his concerns about Mercedes' 2022 car were "wrong".
You can read the full story here.
We have the first red of testing and it appears to be due to a loose drain cover and debris.
Respected F1 journalist Chris Medland reports that "a big chunk of the drain on the entry at Turn 11 has lifted off" after Leclerc's Ferrari ran over it.
An improvement for Hamilton, who jumps up to sixth place in the timesheets.
However, the seven-time world champion, who has completed nearly 40 laps in his W15, is still 1.5 seconds adrift of Leclerc.
Sargeant just ran too deep into the final corner and drifted off track, but managed to gather his Williams back up again without further drama.
Long runs are the current order of the morning, with most drivers carrying out race simulations for their teams.
However, Zhou has just pumped in a personal best to move up to fourth in the timesheets in his black and green Sauber.