Chris Medland
F1 journalist in Barcelona

It’s a cold start to the final day of the first test, and it seems the early morning conditions this week have caught a few drivers out. The latest is Lando Norris, who has ended up in the gravel at Turn 5.

Norris had just completed an out lap and backed off over the finish line so wasn’t travelling particularly quickly, and tyre temperatures don’t take long to drop off. He looks a little sheepish as he walks back to the McLaren garage.

If you look very closely, you can see him...

Romain Grosjean is first to set a lap time - 1:20.851.

All three red flags yesterday were caused by the Haas cars stopping on the track.

The team boss Gunther Steiner says: "we need to get rid of these failures".

Yes, yes you do.

Image source, PA

Quite cold, according to the teams...

Chris Medland
F1 journalist in Barcelona

All eyes remain on Williams this morning. Not only because of the new car but also the man driving it.

Robert Kubica’s comeback after eight years out due to severe injuries sustained in a rally accident is remarkable, with the Pole still learning how close to his previous performance level he can get.

And with Kubica comes a hugely committed fan following. Polish flags and dedicated supporters follow him around the world, even when he isn’t driving. That ended up being the case yesterday, but these guys are already in place this morning too ahead of Kubica’s first drive of the FW42.

They shouldn’t have long to wait either, with Williams having added new parts overnight and now fitting aero rakes ahead of the start of the day’s running.

Williams have both of their drivers out today. Robert Kubica is out in this morning's session.

Lando Norris goes off into the gravel at Turn 5published at 08:29 Greenwich Mean Time 21 February 2019

08:29 GMT 21 February 2019

I feel like we've all done that this week.

Image source, Getty Images

Mercedes - Lewis Hamilton and Valtteri Bottas

Ferrari - Charles Leclerc

Red Bull - Pierre Gasly

Renault - Daniel Ricciardo and Nico Hulkerberg

Haas - Romain Grosjean and Kevin Magnussen

McLaren - Lando Norris

Racing Point - Lance Stroll

Alfa Romeo - Antonio Giovinazzi

Toro Rosso - Alexander Albon

Williams - Robert Kubica and George Russell

They say: "Daniel (Ricciardo) is in the car this morning and will focus on a number of shorter-based runs on softer tyres. It's a cold start so the early running will be about warming up."

Ricciardo mentioned yesterday, the track is like ice in the morning, which explains why there's been a few spins into the gravel early in the morning.

Image source, Getty Images

Andrew Benson
BBC Sport’s chief F1 writer

Pre-season testing will reach its halfway point at the end of today, and perhaps two questions hang heaviest in the air at the Circuit de Barcelona-Catalunya.

One, after what deputy team principal Claire Williams has now described as their “embarrassing” start to the season, is what sort of pace the Williams will show on, this, its first proper day of testing. And the other, remarkable as it may seem to ask, is, what’s going on at Mercedes?

The world champions have always shied away from headline-setting lap times in testing, preferring to go about their preparations quietly and under the radar. But rarely have they looked as under the radar as they have so far in 2019. The car looks a bit of a handful out on track, it has not set any particularly eye-catching lap times, and reading between the lines of Lewis Hamilton’s news conference on Wednesday, you could be forgiven for thinking Mercedes are on the back foot. Will it still look that way by the end of today?

Ferrari set the quickest lap times at the beginning of the week, which were shot at by Kimi Raikkonen in the Alfa Romeo yesterday, and then Daniil Kvyat ended the session with a brilliant lap to take the top of the table.

It's me again, for the fourth day of testing, the final day of this week - or alternatively, the half way point during these eight days.