Image source, PA

Good news McLaren and Jenson Button fans. The team believe they've fixed the issue which has limited Button to just a handful of laps and they are hopeful of getting the MP4-30 out again before the end of the day. Watch this space.

Image source, AP

Ferrari say they spent the morning concentrating on set-up work and tyre testing, running the medium compound. The plan is to continue with that programme after lunch.

World champion Lewis Hamilton peeled into the pit lane and stopped at the entry area. His Mercedes team say it was a minor water system problem, adding: "Expecting to have him back out in a jiffy."

F1 journalist Dan Knutson in Jerez: "Here's a close-up look at the nose of the Red Bull minus the front wing. That certainly has hampered the amount of running Daniil Kvyat can do today. With three hours to go he had done just 14 laps."

Image source, Mercedes

It might be his day off from driving, but Mercedes' Nico Rosberg has chosen to spend it at the track anyway, keeping an eye on the action from the pit wall.

After a flurry of laps, Lewis Hamilton heads back to the pits, leaving Valtteri Bottas with the track to himself. Hamilton remains second fastest but is closing on his century of laps for the day.

Image source, AP

Williams' Valtteri Bottas ups the pace to clock a 1:24.131, which is good enough for third, 3.1 seconds off the pace set by Sebastian Vettel's Ferrari.

So if you're just joining us today, here are the headlines:

• Sebastian Vettel sets the pace in the Ferrari

• Lewis Hamilton continues Mercedes' strong form, clocking up more than 70 laps

• Red Bull's running limited after Daniil Kvyat breaks front wing

• The new Lotus takes to the track for the first time

• McLaren's struggles continue as Jenson Button manages just a handful of laps

Image source, Williams

Williams:, external Both car and driver are refuelled and ready for the afternoon in Jerez.

Andrew Benson
Chief F1 writer

"Much has been made of Red Bull chief technical officer Adrian Newey's decision to step back from F1 this year; perhaps too much, really. Newey, it has become clear from news conferences with the man himself and Red Bull team principal Christian Horner in recent days, has sketched out the fundamental surfaces of this Red Bull, just as he has all the others since he joined the team.

"He will now be splitting his time 50-50 between F1 and his other projects for Red Bull Technologies. But as chief engineering officer Rob Marshall said, that merely means they talk face to face 'every other day rather than every day'.

"What are Newey's other projects? One, already announced, is to help Ben Ainslie's America's Cup bid. The other, which the company have not publicly confirmed yet, is a Red Bull road car."

F1 journalist Dan Knutson in Jerez: "This is parked between the Ferrari transporters in the paddock. Has Ferrari delivered Sebastian Vettel's new company car to the circuit?"

Max Verstappen has popped out for a spin in the Toro Rosso, with Lotus' Pastor Maldonado not too far behind.

Image source, PA

Mercedes' Lewis Hamilton moves his lap tally past 70 before heading back to the pits after another long run. He's soon joined by the Toro Rosso of Max Verstappen, which means the track falls quiet.

Now seems like a good time to grab lunch. I wonder if Hamilton will have his in the car, like his team-mate Nico Rosberg did yesterday?, external

Andrew Benson
Chief F1 writer

"It is traditional on the first day of testing for all drivers to report that their cars are a step forward over last year's. And so it was in Jerez.

"Red Bull's Daniel Ricciardo spoke of 'good first impressions'. Williams's Valtteri Bottas said, 'The car was working well and reliable and the initial feeling was good with the car'.

"Sauber's Marcus Ericsson - second fastest overall, presumably on a low-fuel special, said he had had a 'very good day'. And so on. Time, of course, will reveal all. Not everyone will end up happy, that's for sure."

Image source, PA

And here's a shot of Daniil Kvyat in the Red Bull, which is running without a front wing after the Russian damaged it in a "small off".

Image source, McLaren

Jenson Button is rocking a cool new lid for his 16th season. What do you think?

Image source, McLaren

McLaren:, external Jenson's run a couple more laps - chasing a recurring problem. Hopefully out again soon. #Jerez #TestingIsTesting.

Mercedes' impressive reliability continues as Lewis Hamilton clocks up his 50th lap - that means the world champions have done more than 200 laps in a little under a day and a half. That's considerably more than any others have managed.

F1 journalist Dan Knutson in Jerez: "Williams' chief technical officer Pat Symonds has been talking to the media today. When BBC F1 pit-lane reporter Tom Clarkson asked if Williams can win races this year, Symonds replied: "That's what we are here for, so that is what we are going to be having a damned good go at trying to do."

Andrew Benson
Chief F1 writer

"If Mercedes' performance impressed the media throng, their rivals seemed a bit more nonplussed. Red Bull's Daniel Ricciardo said it was 'no surprise', adding: 'They had an awesome package last year and it's just refining and improving that. But I'm not intimidated either. It's a reachable target.' And McLaren's Fernando Alonso said he felt Mercedes would not win as much this year as last.

"'Definitely they have an advantage of performance and everything for this year at least to start the season,' the Spaniard said. 'But it is normal. They have a continuation of a dominant car, so it is a little bit easier compared to us, when we have a new power unit and very extreme, aggressive car design. I don't think Mercedes will win so many races this year. They are the favourites, yes, but the other teams we are more prepared than last year.'"