This may hurt, says Hamilton as F1 gets back on track

"In days to come, we will start to improve the auto".

The Finn completed 79 laps before turning the auto over to new teammate Lewis Hamilton, a midday swap Mercedes plans to replicate for the remaining three days of this week's test.

The gym work and outdoor training, and the kilos of extra muscle added to cope with new regulations bringing significantly faster cornering speeds and greater G-forces, will be put to the test over four days this week.

Red Bull driver Daniel Ricciardo didn't do much better, getting through just four laps before his new RB13 auto ground to a halt near Turn 4 because of what the team called "a sensor issue".

Vettel topped the timesheets in the first session but the Briton Hamilton, taking over the wheel of Mercedes' imposing 2017 vehicle from new teammate Valtteri Bottas, clocked the day's best lap of 1min 21.765sec. "It's got an engine, four tires, and a steering wheel so yeah, it was very good to test it in the morning".

"It's been a good day, a positive day for the team, lots of laps, lots of information that we've gained so we can try to improve the auto", he added. Obviously I started in a bit more than a month ago but what I've seen has been very impressive and how well the auto has been running it's been impressive and hopefully stays that way.

Sergio Perez was seventh ahead of Carlos Sainz, Nico Hulkenberg and Fernando Alonso, who covered just one lap before lunch as his McLaren-Honda succumbed to an oil system problem.

As such, no team begins by trying to set the fastest possible lap times.

"Mercedes also looks very nice".

Daniel Ricciardo logged 50 laps.

Daniel Ricciardo lost most of the morning after a sensor issue stopped the Red Bull RB13 on track, and a subsequent battery problem caused further delays. Bottas' morning time left him in fifth place at the end of the day after the Finn ran 79 laps.

American team Haas will take away plenty of positives from their performance with Kevin Magnussen producing the fourth-quickest lap.

Williams also managed a lot of running with Felipe Massa posting 103 laps and finishing third.

Vettel stuck to the "medium" compound of tyre for most of the day before a brief run on the "hard", so on the face of it his lap time looks impressive.

  • Lila Blake