All 10 teams hit the track at the Bahrain International Circuit on Friday for the first day of pre-season testing, as they began their programmes to iron out any issues with they new cars before the first race of the year.
Friday morning saw Sebastian Vettel test for Aston Martin, Daniel Ricciardo take the wheel of the Mercedes-powered McLaren and Mick Schumacher make his debut for Haas – who officially unveiled their VF-21 ahead of the session.
As for Mercedes, Valtteri Bottas was hampered by a gearbox issue that kept him confined to the garage for much of the session.
Not all the drivers tested on day one, with Williams duo George Russell and Nicholas Latifi having to wait as test driver Roy Nissany opened the weekend for them, but they did pose for a pre-season photograph as the sun beamed down on the track.
Check out the gallery above for the best images from the test – we'll be adding more pictures throughout the day.