Sebastian Vettel ended the first day of pre-season testing on top of the timesheets, as his lap from the morning session remained unbeaten.
The German set a 1:18.161, which was half a second quicker than Carlos Sainz, who ended the day in second place. Both men set over 100 laps, with Vettel setting the most of any single driver - 169.
Romain Grosjean was third fastest heading the Red Bull of Max Verstappen. The energy drink squad will be pleased with its day, as it started its on-track relationship with Honda by setting 128 laps.
Kimi Raikkonen was fourth from Alfa Romeo, recovering from a spin in the morning. The Finn lost the rear of his car and found himself stuck in the gravel. Behind the 2007 world champion in sixth place was Daniil Kvyat, who makes his full-time return to F1 this season.
Sergio Perez was seventh for Racing Point, who headed the two Mercedes. Valtteri Bottas drove the morning session for the Silver Arrows, before teammate Lewis Hamilton took over in the afternoon. Bottas' time was 0.008s quicker than the four-time world champion's.
Rounding out the timesheets was the Renault duo, as Nico Hulkenberg, who took part in the morning session, ended the day ahead of Daniel Ricciardo who ended bottom of the lot. Williams did not take part in testing, and will not do so until Wednesday.