Nico Rosberg was comfortably fastest on the opening day of testing at the Circuit de Catalunya on a productive day for Williams.
A quick time of 1:24.374 - set in the morning session on unmarked Pirelli tyres - went unbeaten throughout the day as Mercedes finished top. Rosberg's time was actually 0.3s quicker than his pole lap in qualifying on Saturday, partly thanks to improved conditions and an increased grip level, but may also have been aided by softer tyres. However, it was still some way short of the 1:22.792 he set in pre-season testing on the soft compound.
Rosberg was also the busiest driver in terms of lap count as he finished the day with 146 laps to his name, one of five drivers to break the 100-lap barrier on an uninterrupted day of running in Barcelona.
Marcus Ericsson was second quickest for Sauber after improving in the afternoon session following a delayed morning, but his best lap of 1:26.624 was still over two seconds slower than Rosberg's benchmark. Ericsson finished the day with 98 laps after consistent running after lunch.
Ferrari's Raffaele Marciello was third quickest, 0.024s slower than Ericsson on his first run in the SF15-T. Having completed 125 laps, Marciello will switch to the Sauber on Wednesday as part of his duties as reserve driver for the other Ferrari-powered team.
Daniil Kvyat also made it to the 100-lap mark despite a slow start to the day for Red Bull. After an early burst of eight laps, Kvyat spent much of the morning in the garage but his afternoon was much more productive as he set a best time of 1:26.904.
Pastor Maldonado was fifth for Lotus after spending part of the day working on set-up options for the upcoming Monaco Grand Prix, finishing Tuesday just 0.058s quicker than Force India debutant Nick Yelloly.
Yelloly - who was called up to drive a day earlier than planned due to Pascal Wehrlein suffering from a fever - completed 109 laps on his first day in an F1 car and was three seconds away from Rosberg's fastest time. The British driver is attempting to earn a reserve driver role with the team after impressing in the simulator.
Pierre Gasly was another debutant but his day ended with a walk back to the paddock after the stopped on track following the chequered flag. Gasly stopped at Turn 4 in what may have been a fuel run-out test following 131 laps.
Felipe Massa was eighth, completing the Williams program in 54 laps on Tuesday, ahead of Oliver Turvey in the McLaren who was over four seconds off the pace but said the team had rectified the issues suffered by Jenson Button in Sunday's race.
Click here for Tuesday's gallery from testing at the Circuit de Catalunya
|4||D. Kvyat||Red Bull||1:26.904||101|
|6||N. Yelloly||Force India||1:27.396||109|
|7||P. Gasly||Toro Rosso||1:27.639||131|