Charles Leclerc topped the morning session from day seven of testing in Barcelona, heading the timesheets with a 1:16.361.
The lap time marks the fastest we've seen at pre-season testing so far this year, and is just two-tenths slower than Lewis Hamilton's pole lap time from the Spanish Grand Prix last year.
Pierre Gasly followed close behind for Red Bull Racing, heading Nico Hulkenberg and Lance Stroll. Mercedes didn't do a proper short run, as Hamilton ended the session in eighth, behind the Alfa Romeo of Antonio Giovinazzi.
Hamilton set the most laps of any driver throughout the session, racking up 84 laps for the Silver Arrows. The Briton will be handing the car over to teammate Valtteri Bottas for the running in the afternoon.
Bahrain International Circuit - Winter testing