Max Verstappen and Red Bull topped the timesheets, over a second clear of the competition after completing a mammoth 142 laps aboard the new RB20.
McLaren’s Lando Norris and Carlos Sainz of Ferrari were best of the rest, with George Russell of Mercedes languishing down in 12th.
Although testing timing needs to be taken with a large pinch of salt, what have we learnt from seeing this year's Formula 1 cars on track for the first time?
Who’s hot and who’s not? Is there any chance of one of the chasing teams catching Red Bull this season?
Our host Bryn Lucas quizzes Autosport’s Matt Kew in Bahrain media centre, and Sam Hall in the UK, to take a deep dive and gauge their reactions to the first day of F1 pre-season testing.