Ferrari's Sebastian Vettel has topped the timesheets after an eventful morning session on the first day of testing at Barcelona.
The four-time World Champion completed 62 laps in the SF70H, with a best time of 1:22.791 on medium tyres compared to his fastest time of 1:22.810 in testing 12 months ago.
— Scuderia Ferrari (@ScuderiaFerrari) February 27, 2017
Valtteri Bottas in the Mercedes W08 finished three tenths behind the Ferrari on softs after clocking up 70 laps at the Circuit de Cataluyna.
Force India's Sergio Perez rounded off the top three with a 39-lap stint and a best time of 1:23.709.
There were plenty of teething problems, though, most notably for Red Bull and McLaren-Honda.
Daniel Ricciardo brought the first red flag of the day when he stopped the RB13 on the approach to Turn Four after only a handful of laps, with the team later revealing that the stoppage was due to a sensor issue.
McLaren also hit some very early trouble as an oil leak in the Honda engine was discovered, limiting Fernando Alonso to a single lap before the MCL32 was back in the garage.
There was a frustrating start, too, for Haas as their VF-17 broke down in the pit lane before Kevin Magnussen suffered a late spin at Turn 10 and damaging his front wing by hitting the barrier.
The afternoon session will see Bottas replaced by Lewis Hamilton as the two Mercedes drivers split duties, while it remains to be seen whether the Red Bull or the McLaren-Honda will make it back out on track.
UNOFFICIAL CLASSIFICATION (END OF MORNING SESSION)
— Formula 1 (@F1) February 27, 2017
Day One Timesheet (morning session):
1) Sebastian Vettel, Ferrari, 62 laps; medium tyres, 1:22.791
2) Valtteri Bottas, Mercedes, 79 laps, soft tyres, 1:23.169
3) Sergio Perez, Force India, 39 laps, 1:23.709
4) Felipe Massa, Williams, 39 laps, 1:25.552
5) Carlos Sainz, Toro Rosso, 18 laps, 1:25.562
6) Nico Hulkenberg, Renault, 22 laps, 1:26.319
7) Kevin Magnussen, Haas, 15 laps 1:26.404
8) Marcus Ericsson, Sauber, 32 laps, 1:26.865
9) Daniel Ricciardo, Red Bull, 4 laps, 1:28.712
10) Fernando Alonso, McLaren, 1 lap, No time
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