The second day of testing is underway at a sunny Circuit de Catalunya.
All ten teams are returning to the track to continue to work through their test programmes and gain an understanding of their new cars.
McLaren and Lando Norris were fastest on the opening day, with a 1:19.568 becoming the benchmark time in this early stage of F1's new era.
15:20: Another red flag. Nikita Mazepin has stopped at Turn 9.
Sounds like the Haas driver stopped on the race track. The car is pretty swiftly returned to the pits and the sesion has resumed.
Lunch: Daniel Ricciardo was quickest at lunch time. Another strong session for McLaren, who went quickest on Wednesday thanks to Lando Norris.
11:25: Red flag! Looks like Sergio Perez has stopped somewhere on track.
That's the first red flag we've had throughout testing so far. Testing stoppages can happen for all sorts of reasons, but the immediate interest around that will obviously be whether this is an issue which costs Red Bull significant track time this afternoon.
Laurence Edmondson, trackside: "Watching the cars on track at the end of the pit straight and it's clear that some (noticeably the Alpine, Williams and Mercedes) are experiencing a phenomenon known as "porpoising" to some extent. From the outside it looks like the car is wobbling up and down on its suspension at high speed, almost like it is going over bumps.
"I'm not a tech journalist, but the theory is that the underfloor of the car is getting so low to the ground due to the downforce acting upon it that it starts making contact, meaning a sudden change in downforce that causes it to rise up again before it loads up once more and moves back down. It's more obvious when the DRS is closed, which is when more downforce is acting on the rear.
"We'll have to wait on some driver and team feedback to see how big an issue it is expected to be, but it may well be a side effect of the new regulations and something that needs to be ironed out by a number of teams."
12:00: Worth remembering that at this stage of testing mileage is probably the more important measuring stick than outright lap times. That's how you can spot which teams might be in a spot of bother. Alfa Romeo had a low lap count yesterday and Valtteri Bottas has only managed 12 laps so far this morning -- it's been another difficult morning for the Swiss team.
By contrast, things on track seem to be much better for Haas. Mick Schumacher has had quite a productive time of things so far, with 53 laps to his name.
Carlos Sainz leads the way for Ferrari by nearly a second, but the next nearest cars are AlphaTauri and Williams. With fuel loads and engine modes unknown at this time it is very much a guessing game until we have more data to go on by the end of the week.
11:00: Sainz remains at the top the timesheets on a 1:20.890 set on the C3 tyres. Pierre Gasly is now second fastest in the AlphaTauri with a 1:21.466 on C3s. It doesn't look like anyone has started pushing yet. Fast times tend to come just before lunch or at the end of the day, but we are currently over a second off yesterday's fastest time and four seconds off the lap record.
10:30: Relatively slow starts to the day for Mercedes and Red Bull, but both cars are now back on track. Lewis Hamilton is in the Mercedes, Perez in the Red Bull. Nothing approaching competitive times as yet...
10:00: Carlos Sainz has set the early pace in the Ferrari ahead of Williams Alex Albon. We've got a handful of drivers making their first preseason appearance this year this morning, including Daniel Ricciardo in the McLaren, Sergio Perez in the Red Bull, Esteban Ocon in the Alpine and Pierre Gasly in the Alpha Tauri. Guanyu Zhou, F1's only rookie this year, will make his 2022 debut this afternoon.