George Russell heading out in his Williams.

It says a lot, since the team have been the biggest topic of discussion this week, and the support from the F1 community speaks positive of the team, plus we finally have a full squad in Barcelona now.

That's it for today...

Daniil Kvyat managed to bag a fast lap time in the final few minutes of this afternoon's session, overtaking Kimi Raikkonen at the top.

Don't forget to vote for your favourite 2019 livery here.

And you can read Andrew Benson's report from day three of testing here.

We'll be back once again at 08:00 GMT tomorrow for the fourth day of pre-season testing.

Image source, Williams Twitter

George Russell, speaking to Sky Sports after today's afternoon session. He says: "Today was more of a shakedown run - we'll get a proper run out tomorrow. Unfortunately couldn't do that before we came here but there we go..."

It's all about understanding the weaknesses of the car, the track is 10-15 degrees so realistically it's not going to be that important."

"I'm doing my best to help the team, in the long run I'm trying to help the team..."

Image source, Reuters

The session ended with a red flag, one again caused by Haas.

What happened today?

• Three red flags all from the Haas' stopping on the track. Two from Romain Grosjean and the other from their development driver Pietro Fittipaldi
• Haas have problems with an ignition-coil
• Carlos Sainz had a spin into the gravel at Turn 14, he hit the brakes and tried to turn in while on the kerb
• George Russell tested the Williams after being two days late to Barcelona
• Daniil Kvyat goes quickest overall, followed by Kimi Raikkonen and Daniel Ricciardo
• Ferrari continue to impress, as Charles Leclerc says "reliability is their strong point"
• Vote for your favourite 2019 livery here

Image source, Reuters

Haas cause another red flagpublished at 16:57 Greenwich Mean Time 20 February 2019

16:57 GMT 20 February 2019

The Haas drivers have spent a lot of the day in the garage, causing all three red flags in today's sessions with their cars grinding to a halt.

... in the Toro Rosso!

Who saw that one coming?

In a time of 1:17.704, the Russian is five hundredths quicker than Kimi Raikkonen.

Daniel Ricciardo and Daniil Kvyat jump up to the top three, as Sebastian Vettel is finished for the day.

1. Raikkonen (Alfa Romeo) 1:17.762 (138 laps)
2. Ricciardo (Renault) 1:18.164 (78)
3. Kvyat (Toro Rosso) 1:18.276 (131)
4. Vettel (Ferrari) 1:18.350 (134)
5. Verstappen (Red Bull) 1:18.787 (100)
6. Hulkenberg (Renault) 1:18.800 (63)
7. Grosjean (Haas) 1:19.060 (60)
8. Fittipaldi (Haas) 1:19.249 (48)
9. Sainz (McLaren) 1:19.354 (90)
10. Perez (Racing Point) 1:20.102 (67)
11. Bottas (Mercedes) 1:20.693 (88)
12. Hamilton (Mercedes) 1:20.818 (86)
13. Russell (Williams) 1:25.625 (21)

Sadly, we don't have the data to give you any tyre information related to these lap times.

Chris Medland
F1 journalist in Barcelona

A solid bit of running for George Russell comes to an end, and he’s pushed back into the garage by a Williams crew that is no doubt delighted to be getting down to some serious work.

One thing that’s obvious is the interest in the car from all teams. Whispers from the team suggest it might not show a great turn of pace, but it’s still the one car that hadn’t been seen until a few hours ago so rival engineers are keen to take a look. Haas are next door to Williams and plenty of their team came out of the garage to see the FW42 as Russell brought it back into the pits.

Lewis Hamilton speaking in a press conference in Barcelona says on his team-mate: "I’m excited for Valtteri (Bottas) and it takes time to really dig your roots into a new team – it’s not an easy process. He has been an invaluable part of the team for the last couple of years and the growth, I think, has been amazing and he has really helped keep us stabilised in terms of positive energy in the team.

"He will continue on that form, but I’m sure he will want to be stronger this season and as a team, collectively, we will support him in every way we can. Me and him have a very good working relationship and we do actually talk about things on the car and work together. I don’t know if I’ve ever had that in the past – we actually really do work together and talk about each other about things, so I hope that continues and we have a strong year together.

“I don’t generally have expectations of anything but I would assume he is going to be more aggressive and I am sure he is going to be pushing harder. He has always been incredibly determined since he got here and that has not wavered. I’m sure he knows what he has to focus on.”

Image source, Getty Images

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Image source, Getty Images

Your turn...

Inge: Re 15:59: Cyril Abiteboul says "What did you say, no lobster for dinner?"

Robert Stone: "OK, I admit your F1 engines are slightly faster than the Renault Twizzy - but there's not a lot in it"

Micky-boy: "When I said 'Fancy a Red Bull?' I meant a drink. Not our Aussie driver you cheeky blighter!"

Paul Hill: Are you having a laugh Cyril. Geri said no freebies for the spice girls tour for Renault.

CJEd: "The problem is Christian, you have to put petrol in the engine not Red Bull"

Andrew Benson
BBC Sport’s chief F1 writer

Haas have changed their schedule for tomorrow after the stoppages that have plagued Romain Grosjean today. The Frenchman will now drive on Thursday morning as well, with Kevin Magnussen taking over in the afternoon. Grosjean has been stopped on track twice today by the same problem - a problem with the ignition coil.

Daniil Kvyat has come to a halt at the end of the pit lane. Meanwhile Haas have an ignition-coil related issue.

Then Kimi Raikkonen comes slowly rolling into the pit lane, while, George Russell slides off the track in the Williams. No drama, no damage, he just continues the lap.

Andrew Benson
BBC Sport’s chief F1 writer

Claire Williams won't explain why the team's car was not ready to run until today, other than that parts did not come through the system in time, but she will say how she feels about it, and she is not pulling any punches: "We’re not just disappointed. It’s embarrassing not bringing a race car to a circuit when everyone else has managed to do that, particularly a team like ours that has managed to bring a race car to testing for the past 40-odd years." She says she wants to apologise to the team's fans and most of all to drivers George Russell and Robert Kubica.

Finally getting out on track was "a big relief", she says. And she dodged a question about the future of chief technical officer Paddy Lowe: "I've read a lot of speculation about his position. Right now all I am focused on and the team should be focused on is making sure the car is in the right place."

Image source, Getty Images

Chris Medland
F1 journalist in Barcelona

It has been a rough week so far for Williams, but George Russell is finally getting some laps on the new FW42 this afternoon. Facing the media, Claire Williams says she just wants to focus on making up for lost time and says a proper review and investigation will take place at a later date.

For now the team is still waiting on aero parts to get down to proper work on Friday. Robert Kubica's first run will be a half day on the final day of this week's test on Thursday.

George Russell has posted some lap times in the Williams - the quickest so far: 1:49.830. Which is just over 32 seconds slower than Kimi Raikkonen in the Alfa Romeo at the top of the board. But at this point in the week, we all know by now not to take lap times too seriously in testing.

Andrew Benson
BBC Sport’s chief F1 writer

World champion Lewis Hamilton expects a tougher challenge from Ferrari in Formula 1 this season.

Read more here.

Just on this, there is a lot of talk about "Oh, Ferrari are always quick in testing." Well, yes.

But last year on day one, Bottas was second and ahead of Raikkonen, on day two Vettel was quickest by 0.3secs from Bottas, and Hamilton was fastest on day four, nearly one second quicker than Vettel.

I'm not saying anything should be read into this, but in terms of headline pace so far, Ferrari are quicker by comparison to Mercedes than they were last year. For what that's worth.

Charles Leclerc, speaking to Sky Sports says: "It's very good to be back and I'm happy with how its going. Reliability is our strong point for now, we are on different run plans and we went through the plan we wanted every day so far, so hopefully we can continue with this."

Image source, Reuters

Chris Doherty: The red O Rokit combined with the blue and white makes the Williams look like a dishwasher tablet with a Powerball.

BlueMarbleRider: Given the lackluster Merc pace so far, it will be interesting to see who is the quickest the English driver this season...Norris is looking quick and, who knows, wouldn't it be nice to Russell in a Williams dent some egos...

Graham Wright: What's going on with Mercedes? Is there any reason they're near the bottom of the timings?

Andrew Benson
BBC Sport’s chief F1 writer

Lando Norris had a good first day as a full-time McLaren driver on Tuesday, ending the day second fastest to a Ferrari, just as team-mate Carlos Sainz had on the first day of the test. The 19-year-old said the main focus for him at the moment is getting into the swing of things in F1. “Whether I can beat (Sainz) or not is not really the question for me at the moment,” Norris said. “It is looking at his data from yesterday and tomorrow, his performance runs and long runs and being where I can improve. It is about keeping my positives and the things I am good at and combining with the things he’s good at so I don’t get beaten.”

McLaren had some well publicised aerodynamic flaws with their car in 2018. Have they fixed them yet? Not completely, it seems. “Overall it is a different car and it is very different in terms of aero, with the (rule) differences,” Norris said. “Some things we’ve improved on, but there is a lot to work on, a lot of stuff we have learned the last two days that we need to fairly quickly develop and improve on for the rest of the test and the first race. It is hard to say all the problems have gone. There are still some things we struggle with. It is not a perfect car for sure but we are reasonably happy so far.”

Image source, PA