Nico Rosberg set the quickest time of pre-season testing at Barcelona so far to top the second day of running at the Spanish track.
Rosberg's 1:22.792, set on soft tyres, was over 1.2 seconds quicker than the Williams of Valtteri Bottas, second fastest today.
Morning pace-setter Felipe Nasr dropped down to third in the afternoon, but still had a solid day of running with 140 laps covered.
The Brazilian finished ahead of four-time champion Sebastian Vettel in the Ferrari, the German another driver to complete over 100 rounds.
McLaren enjoyed its best day of pre-season testing so far following yesterday's problem, with Jenson Button covering over 100 laps for the first time this year.
The day, however, was not without trouble for the Honda-powered team, as Button caused a red flag near the end of the session when he stopped on track.
Lotus driver Pastor Maldonado caused another stoppage minutes later, the session coming to an early end.
Max Verstappen drove the heavily updated Toro Rosso STR10 for the first time, but the Dutchman's day also came to an early finish due to electrical problems.
But Verstappen was very encouraged with his progress after a mammoth 139 laps recorded.
"Another good day as we did a lot of laps," said Verstappen. "From my perspective, the most important part was this afternoon's race distance, when the pace looked very promising.
"It was my first time driving the car with the latest updates and they seemed to be working very well and I felt very comfortable with it."
Sister team Red Bull's day was not as productive, with Daniil Kvyat down in eighth place after 80 laps.
The Russian caused one of the three red flags of the day when he stopped at Turn 1 shortly after the lunch break.
Nico Hulkenberg finished at the bottom of the times in what was the new Force India's track debut.
Although he managed just five laps in the morning, the German driver and his team had a productive maiden run in the Mercedes-powered VJM08, completing over 70 laps on the day.
|7.||Max Verstappen||Toro Rosso-Renault||1:26.766||+3.974||139|
|8.||Daniil Kvyat||Red Bull-Renault||1:26.965||+4.173||84|
|9.||Nico Hulkenberg||Force India-Mercedes||1:28.412||+5.620||77|