His Ferrari team had decided to devote some of its programme on Tuesday to getting to the bottom of its recent qualifying woes, and especially how best to extra more performance from the tyres.

Much of his day was spent focusing on qualifying simulations with the soft tyres, and it was on one of these runs in the afternoon that Vettel set a best lap of 1m23.220 seconds.

During qualifying in Spain on Saturday, when Ferrari's promising pace vanished as track temperatures rose, Vettel had only been able to deliver a 1m23.334s lap, which points to his team having unlocked some answers at least as to what went wrong.

Nico Rosberg ended the day second fastest on soft tyres with a 1m23.337s lap, although spent much of the day on medium rubber as he completed a busy day of car evaluation.

Jenson Button's morning time on super soft tyres of 1m23.753s remained his best lap – and the third fastest time overall – as he continued mechanical and aerodynamic work for McLaren.

Romain Grosjean did an ultrasoft run in the afternoon to set the fourth fastest time of 1m23.882s for Haas, as the outfit experimented with set-ups to try to better extract more pace from its tyres.

Wehrlein also did a qualifying sim on the supersoft late in the afternoon to set the fifth fastest time for Manor.

Sixth fastest Daniel Ricciardo was able to complete some decent running in the afternoon as Renault continued to put the mileage on its upgraded engine that was being run for the first time.

The Australian switched to soft tyres in the afternoon to set a best lap of 1m24.307s, and is due to hand the car over to new teammate Max Verstappen for Wednesday's second day.

Red Bull junior driver Pierre Gasly was seventh fastest for Toro Rosso on soft tyres, just ahead of Force India's Alfonso Celis Jr who put in a late lap on super soft tyres.

Williams test driver Alex Lynn was ninth fastest. Following the morning run of a radical front and rear wing set-up to simulate 2017 downforce levels, Lynn completed a more normal test programme early in the afternoon. However, the double decker rear wing arrangement returned for the final runs of the day.

Renault reserve Esteban Ocon completed 105 laps for the team to end the day 10th fastest overall.

Day 1 results

Pos. Driver Team Time Gap Laps 1 Sebastian Vettel Ferrari 1:23.220 103 2 Nico Rosberg Mercedes 1:23.337 0.117 119 3 Jenson Button McLaren 1:23.753 0.533 86 4 Romain Grosjean Haas 1:23.882 0.662 96 5 Pascal Wehrlein Manor 1:24.297 1.077 86 6 Daniel Ricciardo Red Bull 1:24.307 1.087 89 7 Pierre Gasly Toro Rosso 1:24.821 1.601 78 8 Alfonso Celis Force India 1:25.467 2.247 99 9 Alex Lynn Williams 1:26.071 2.851 86 10 Esteban Ocon Renault 1:26.530 3.310 105





