F1's Marathon Man, Felipe Massa, is on the circuit as he takes over from Lance Stroll for the afternoon.

Valtteri Bottas, another afternoon replacement as he replaces Lewis Hamilton, takes the Mercedes out for a lap.

Image source, .

F1 journalist Dan Knutson: The increased downforce on the cars this year means that the drivers can brake later for corners than they did last year. 

“The braking forces will also be higher,” Adrian Newey said. “What that does to overtaking is a little bit of a concern. It means braking distances will be very short.” 

I watched the cars from the grandstand overlooking the end of the back straight. The drivers are braking very, very late into Turn 10.

Daniil Kvyat does a 1:25.936 on the softs. He's now been joined on the track by Esteban Ocon.

Phil Evans: Get out and push?  

Josh McEnerney: He should quit F1 & go to Indy Car because he's not going to get a winning car. Best driver around but his time is up!  

James Cummins: Getting increasingly annoyed with Mclaren's woes. Constant problems, especially with the powerunit. No wonder Alonso's miffed.

Daniil Kvyat isn't doing the Dan dance because he's out on the circuit - the only driver who is at the moment. 

He's got softs on his Toro Rosso.

Image source, Getty Images

Oh yeah, teaser answer. The man in the swirly thing at 12:24 GMT is indeed Wilson Fittipaldi Junior. Only gets presents once a year, poor chap.

He's on the right in this picture. That's his lad Christian on the left.

Ten minutes into the afternoon session and no-one has ventured out yet.

They can't all be gleefully twirling their arms around like Daniel Ricciardo, can they?

Andrew Benson
Chief F1 writer

Right, now the dust has settled after that little pre-lunch lap-time excitement, let’s have a little think about what it might all mean. Sebastian Vettel set a 1:19.0 on ultras and a 19.3 on super-softs in the Ferrari. But a) it seems he may have deliberately backed off on both those laps; and b) he did a 19.3 on the softs - which should theoretically be at least a second slower than the ultras and 0.6-0.7secs off the supers. So let’s take that 19.3 as his benchmark. 

Meanwhile, Lewis Hamilton did a 19.3 on the ultra-softs. But we already know he can do at least a 19.84 on the softs from Tuesday.

In theory, that puts the Ferrari 0.5secs up on the Mercedes. However… Traditionally, Ferrari run less fuel in their cars in testing than Mercedes do. Of course it’s possible that they have changed that, but let’s assume for a moment that both teams are doing the same as normal.

Mercedes are widely believed to run about 60kg of fuel in their car in testing - that’s two seconds’ worth; Ferrari about 30kg - that’s one second.

So  if that’s the case here, Vettel’s potential quickest lap on qualifying-level low fuel is an 18.3 on softs. Hamilton’s is a 17.8. A half-second advantage for the Mercedes. Which based on recent history, is probably about what would be expected. Perhaps that’s why Vettel said Ferrari have a lot of work to do...

Sorry for the brief lull in entries, I foolishly offered to make a round of teas and when people are supposed to say "no thanks" they actually said "yes please". Five brews later...

Anyway, the afternoon session is under way.

Andrew Benson
Chief F1 writer

Sebastian Vettel was seen apparently backing off at times on his quickest laps. Asked if he was doing that deliberately to disguise Ferrari's pace, he said: "It's not always intentional. You could see what we were trying to do this morning. We were going faster than the rest of testing.

"I feel pretty happy inside the car but it is still early days. You need to look at more than one single lap time. We still have a lot of work to do. The team is working very hard. last year's experience has in many ways helped us to grow as a team. hopefully we can carry that into this year."

F1 journalist Dan Knutson in Barcelona: Renault is doing a precautionary engine change. They started a couple of hours ago.

Stuart Clark: If you do a search for 25/12, you get only Giancarlo Baghetti.

That's called cheating Stuart. Back of the class you go.

And it's not Baghetti.

Andrew Benson
Chief F1 writer

Honda say an electrical issue stopped the car both times today. That's also what they said was the problem on Tuesday.

Image source, Getty Images

Let's see if this is any tougher then.

I am one of only two people born on 25 December to race in Formula 1.

I entered 38 F1 races in my three seasons in the sport.

I competed for two teams.

Who am I?

Answers to #bbcf1

Image source, @F1

1 Sebastian Vettel (Ger) Ferrari 1:19.024 *** 

2 Lewis Hamilton (GB) Mercedes 1:19.352 *** 

3 Esteban Ocon (Fra) Force India 1:20.161 *** 

4 Daniil Kvyat (Rus) Toro Rosso 1:20.416 ** 

5 Daniel Ricciardo (Aus) Red Bull 1:20.824 * 

6 Kevin Magnussen (Den) Haas 1:20.863 ** 

7 Stoffel Vandoorne (Bel) McLaren 1:21.348 *** 

8 Jolyon Palmer (GB) Renault 1:22.418 * 

9 Marcus Ericsson (Swe) Sauber 1:23.330 *

 10 Lance Stroll (Can) Williams 1:24.863 *

 *** = ultra-soft tyre; ** = super-soft; * = soft

F1 journalist Dan Knutson in Barcelona: Yusuke Hasegawa, Honda’s Head of F1 Project & Executive Chief Engineer, has flown to Japan where he will be at Honda’s F1 factory in Sakura to personally oversee the work on the much-needed updates to the power unit.

Andrew Benson
Chief F1 writer

Ferrari’s Sebastian Vettel set the fastest time of the winter on the penultimate day of the final pre-season Formula 1 test.

The four-time champion’s time of one minute 19.024 seconds was just under 0.3secs quicker than the previous best set by Mercedes driver Valtteri Bottas.

Vettel, who set his quickest lap on the ‘ultra-soft’ tyre was also impressive in being just 0.3secs slower on the ‘soft’. The ‘ultra-soft’ is said to be about 1.2secs fastest than the soft.

Mercedes driver Lewis Hamilton was second fastest, 0.328secs behind Vettel, also using the ultra-soft.

Meanwhile, McLaren-Honda continue to struggle. Stoffel Vandoorne set the team’s fastest time of the winter on Thursday morning - 2.3secs slower than Vettel. But the car broke down on track shortly before the end of the morning session.

Unlike previous problems, Vandoorne was able to return to the track not long afterwards - only to break down again straight away.