Ferrari's Sebastian Vettel leads penultimate day of test

The German driver set the fastest time of the winter yet on Thursday morning with a 1m19.024s on ultra-softs.

Despite there being more than a hint of sandbagging from Ferrari, that was almost three tenths up on Valtteri Bottas's previous best, recorded on Wednesday.

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Vettel's effort went unbeaten in the afternoon, as the top runners focused on completing race simulations, and it was the Ferrari driver who topped the lap count as well as the times, racking up 156 laps.

Morning times were also enough to keep Lewis Hamilton second for Mercedes, ahead of Force India's Esteban Ocon and Daniil Kvyat, who caused the first red flag of the afternoon when his Toro Rosso ground to a halt at Turn 5 around 90 minutes into the session.

Kevin Magnussen moved up to fifth in the Haas with a best time of 1m20.504s on ultra-softs, the best lap of the afternoon.

That demoted Red Bull's Daniel Ricciardo and McLaren's Stoffel Vandoorne to sixth and seventh, as neither improved on their personal bests from earlier in the day.

After his two stoppages in the morning, both caused by electrical issues, Vandoorne left the garage with around two hours of the afternoon remaining, but managed only a further 16 laps on top of the 32 he logged before lunch.

Bottas, taking over the Mercedes W08 from Hamilton for the afternoon, was eighth fastest with a best effort of 1m21.819s set on softs, which left him 2.795s off the pace of Vettel.

The Finn completed 95 laps, giving Mercedes a total of 147 for the day.

Sauber's Pascal Wehrlein and Marcus Ericsson were ninth and 11th for the day, split by Renault's Jolyon Palmer, who managed only 53 laps.

The Briton was responsible for the afternoon's second stoppage - and fourth of the day - when he came to a stop at Turn 10 following a power unit change.

Nico Hulkenberg was originally scheduled to take over the Renault after lunch, but the change of engine combined with Palmer's problem meant he never appeared on track.

Williams pair Felipe Massa and Lance Stroll propped up the times but did not complete any performance running as they logged 165 laps between them.