Mercedes have become the latest team to confirm their driver line-up for Wednesday's track time at the Circuit de Barcelona-Catalunya.
While most of the teams so far have confirmed their line-ups for all three days of testing, Mercedes have opted to announce their plans for just the opening day.
George Russell has been given the honour of the first go with the new W13 on track, with the British driver taking the wheel for the morning session.
At lunchtime, Russell will climb out and hand over the W13 to Lewis Hamilton – the seven-time World Champion will drive for the afternoon.
Mercedes' driver plans for Thursday and Friday will be confirmed in due course.
With F1 pre-season testing getting underway in Barcelona this week, our journalists Dieter Rencken, Mike Seymour and Thomas Maher look ahead to what to expect.