Mercedes’ Valtteri Bottas clocked the quickest time on the third day of pre-season testing at the Circuit de Barcelona-Catalunya, as he sampled Pirelli’s Ultra Soft tyres.
Bottas set a sub 1:20s lap time on the Super Soft tyres during the morning session before going even quicker on the Ultra Softs, setting a 1:19.705, to end the day atop the times.
Ferrari’s Sebastian Vettel emerged as his closest challenger, 0.247s adrift, having registered his quickest time on the Soft compound.
Vettel accrued 138 laps for Ferrari, the most for a single driver, before coming to a halt on the pit straight with 10 minutes remaining of the day.
Daniel Ricciardo finished third for Red Bull as he took over duties from Max Verstappen, with his programme briefly halted while a suspected exhaust issue was investigated.
Renault's Jolyon Palmer spun into the gravel on the approach to Turn 3 early in the morning in cold conditions, causing the session to be halted, but soon returned to action, finishing fourth.
Nico Hülkenberg took over from his team-mate for the afternoon session and placed fifth, ahead of Marcus Ericsson, who completed 125 laps for Sauber.
Lewis Hamilton placed seventh overall, driving in the afternoon, with his race simulation interrupted when Toro Rosso’s Carlos Sainz Jr. stopped in the gravel at Turn 4.
Hamilton’s lap count, combined with Bottas’, ensured Mercedes led the mileage charts again, completing 170 laps.
Romain Grosjean received his first taste of Haas’ VF-17, after Kevin Magnussen opened test proceedings for the team, and placed eighth.
Williams rookie Lance Stroll endured another challenging day, despite managing to rack up almost 100 laps in the FW40.
Stroll spun off in the second sector during the closing stages of the morning session, before he crashed out of the afternoon running with two hours remaining on the clock.
Stroll lost control of his Williams exiting the left-hander at Turn 5 and clouted the barriers on the outside of the circuit, sustaining irreparable damage to his car.
McLaren-Honda enjoyed a far more productive day as Fernando Alonso was able to complete 72 laps in the MCL32, a vast improvement after troubles across the opening half of the test, though its best lap was 2.8s off the pace.
Sainz Jr. finished 11th, not returning to the circuit after his off, while Force India development driver Alfonso Celis Jr. was given duties in the VJM10 and finished 12th.
Daniil Kvyat completed the morning session for Toro Rosso and finished at the foot of the standings, 4.2s off Bottas’ benchmark.
| Pos | Driver | Team | Time | Gap | Tyre | Laps |
| 1 |  Valtteri Bottas |
Mercedes | 1:19.705 |  |
75 | |
| 2 |  Sebastian Vettel |
Ferrari | 1:19.952 | 0.247 |  |
139 |
| 3 |  Daniel Ricciardo |
Red Bull | 1:21.153 | 1.448 | |
70 |
| 4 |  Jolyon Palmer |
Renault | 1:21.396 | 1.691 | |
51 |
| 5 | Nico Hulkenberg |
Renault | 1:21.791 | 2.086 | |
42 |
| 6 |  Marcus Ericsson |
Sauber | 1:21.824 | 2.119 |  |
126 |
| 7 | Lewis Hamilton |
Mercedes | 1:22.090 | 2.385 | |
95 |
| 8 |  Romain Grosjean |
Haas | 1:22.118 | 2.413 | |
56 |
| 9 |  Lance Stroll |
Williams | 1:22.351 | 2.646 | |
98 |
| 10 |  Fernando Alonso |
McLaren | 1:23.598 | 3.893 | |
72 |
| 11 | Carlos Sainz |
Toro Rosso | 1:23.540 | 3.835 |  |
32 |
| 12 |  Alfonso Celis Jr |
Force India | 1:23.568 | 3.863 | |
71 |
| 13 |  Daniil Kvyat |
Toro Rosso | 1:23.952 | 4.247 | |
31 |
