Ferrari’s Sebastian Vettel topped the opening day of the post-Spanish Grand Prix Formula 1 test at Barcelona’s Circuit de Catalunya.
Vettel, third in Sunday’s race, clocked a 1m23.220s on a set of the soft tyres in the afternoon to end the day fastest.
Nico Rosberg smashed the 100 lap mark on route to second on the timesheets for Mercedes, a tenth shy of Vettel’s pace-setting time on the same soft rubber.
Jenson Button was third quickest in the McLaren-Honda, after topping the morning session with a run on the super-softs.
Romain Grosjean jumped to fourth for Haas with a late run on Pirelli’s new ultra-soft compound, which is set to debut at next week’s Monaco Grand Prix.
Manor’s Pascal Wehlein ended the day fifth with 86 laps on the board, narrowly edging out Daniel Ricciardo in the Red Bull.
GP2 points leader Pierre Gasly was seventh, clocking up 78 laps for Toro Rosso, ahead of Force India’s Alfonso Celis Jr.
Gasly’s GP2 rival and Williams reserve Alex Lynn was ninth and spent his day concentrating on development work.
Williams ran a modified front-wing and double-decker rear-wing in the morning in pursuit of 2016/17 data, despite the bodywork layout being outlawed by the regulations.
Esteban Ocon propped up the timesheets for Renault, ending the day with 105 laps on his tally.
The Sauber team opted not to take part in the Barcelona test.
| # | Driver | Team | Time | Laps |
| 1 | S. Vettel | Ferrari | 1:23.220 | 103 |
| 2 | N. Rosberg | Mercedes | 1:23.337 | 119 |
| 3 | J. Button | McLaren | 1:23.753 | 86 |
| 4 | R. Grosjean | Haas | 1:23.882 | 96 |
| 5 | P. Wehrlein | Manor | 1:24.297 | 86 |
| 6 | D. Ricciardo | Red Bull | 1:24.307 | 89 |
| 7 | P. Gasly | Toro Rosso | 1:24.821 | 78 |
| 8 | A. Celis | Force India | 1:25.467 | 99 |
| 9 | A. Lynn | Williams | 1:26.071 | 86 |
| 10 | E. Ocon | Renault | 1:26.530 | 105 |
