Daniel Ricciardo set the pace on the first day of F1 pre-season testing in Barcelona on Monday.
All 11 teams took to the track for the first official running of the 2018 contenders, but it was the Red Bull RB14 - complete with it's new race livery - which set the fastest time of the day.
Ricciardo, who will relinquish the seat for team-mate Max Verstappen to take over on Tuesday, posted a 1:20.179 as a fastest time, nearly two tenths of a second faster than Mercedes' Valtteri Bottas.
The Australian completed 105 laps, more than any of the other 12 drivers. Force India's Nikita Mazepin completed the least with just 22 laps under his belt.
The morning session was dry for the runners, but rain fell during the afternoon session meaning running later in the day was done on wet tyres. Rain and even snow are forecast for later in the week at the Circuit de Barcelona-Catalunya.
World champion Lewis Hamilton took over in the Mercedes running in afternoon from Bottas, and set the seventh fastest time of the day, while the Toro Rosso and Force India cars broke cover for the first time before the green light in the morning.