Red Bull’s Daniel Ricciardo set the fastest time on a murky opening day of testing at the Circuit de Barcelona-Catalunya on Monday.
Ricciardo registered a lap of 1:20.179 during the final five minutes of the morning’s running, held in cool and cloudy weather, and his time remained unbeaten as conditions worsened during the afternoon.
Ricciardo’s lap, set on Mediums, was 0.170s clear of Mercedes’ Valtteri Bottas, who also recorded his quickest time on the white-banded rubber.
Ricciardo was also the only driver to complete over a century of laps, as Red Bull completed the most mileage, narrowly ahead of Renault.
Kimi Raikkonen ensured last year’s leading trio of teams locked out the top three positions, covered by just 0.327s, with his best time coming on the Soft tyres.
Nico Hulkenberg completed running during the morning session for Renault and claimed fourth, while Fernando Alonso was fifth, having recovered from an initial setback.
A wheel nut failure pitched Alonso into the gravel as he rounded the final corner on only his sixth lap of running, with his right-rear tyre detaching in the incident.
The excursion meant Alonso did not appear for several hours, though he returned to the track shortly before the lunch break, and wound up fifth overall*.
Carlos Sainz Jr. tested during the afternoon for Renault and placed sixth, as he garnered his first experience in the R.S.18.
Reigning World Champion Lewis Hamilton took over control of the W09 from Bottas, as planned, for the afternoon session and finished seventh, completing 25 laps.
Toro Rosso-Honda enjoyed a productive first full day of track action since forming its partnership as Brendon Hartley completed 93 laps in the STR13.
The total was the most mileage Honda has accrued on the opening day of a pre-season test since its Formula 1 return in 2015, as Hartley finished in eighth position.
Lance Stroll was ninth for Williams, running in the morning session, as Romain Grosjean rounded out the top 10 for Haas.
Sauber’s Marcus Ericsson was 11th, in front of Force India development driver Nikita Mazepin, the young Russian causing a red flag in the morning session when his VJM11 came to a halt in the gravel at Turn 4.
Williams rookie Sergey Sirotkin tested the FW41 during the afternoon session and wound up at the foot of the times, some 23 seconds off the pace, as he completed aero runs.
*Update: Alonso demoted from fifth to seventh after it was deemed he cut the chicane on his quickest lap.
| Pos | Driver | Team | Time | Gap | Tyre | Laps |
| 1 | Daniel Ricciardo | Red Bull | 1:20.179 |  |
102 | |
| 2 | Valtteri Bottas | Mercedes | 1:20.349 | 0.170 | |
58 |
| 3 | Kimi Raikkonen | Ferrari | 1:20.506 | 0.327 |  |
80 |
| 4 | Nico Hulkenberg | Renault | 1:20.547 | 0.368 | |
73 |
| 5 | Carlos Sainz | Renault | 1:22.168 | 1.989 | |
26 |
| 6 | Lewis Hamilton | Mercedes | 1:22.327 | 2.148 | |
25 |
| 7 | Fernando Alonso | McLaren | 1:22.354 | 2.175 |  |
48 |
| 8 | Brendon Hartley | Toro Rosso | 1:22.371 | 2.192 | |
93 |
| 9 | Lance Stroll | Williams | 1:22.452 | 2.273 | |
46 |
| 10 | Romain Grosjean | Haas | 1:22.578 | 2.399 | |
55 |
| 11 | Marcus Ericsson | Sauber | 1:23.408 | 3.229 | |
63 |
| 12 | Nikita Mazepin | Force India | 1:25.628 | 5.449 | |
22 |
| 13 | Sergey Sirotkin | Williams | 1:44.148 | 23.969 | |
27 |
