HIGHLIGHTS: Watch all the action as the 2021 cars hit the track for Day 1 of pre-season testing

The 2021 cars all hit the track on Friday as pre-season testing got under way at the Bahrain International Circuit.

The teams have just three days of testing this year to fine tune their new challengers before the first Grand Prix of the year – also being held at the Bahrain track – in two week's time.

Other than a few carefully controlled shots of shakedown runs and team filming days, it was our first chance to see the new cars in action, and as ever, it was a mixed story up and down the grid.

READ MORE: Verstappen tops Day 1 of pre-season testing as Mercedes struggle in sandstorm-hit Bahrain

Red Bull topped the time sheets and the lap count with Max Verstappen at the wheel, as their preparations started faultlessly. But things were far from faultless for World Champions Mercedes, who got in just six laps of running in the morning after a gearbox problem, then struggled for grip and pace when they did get going in the afternoon.

Hit play in the video above to see all the key moments from Day 1 in Bahrain...