Mercedes and Ferrari have announced what drivers will be taking to the track next week for the two-day test following the Bahrain Grand Prix. In-season testing is very rare in modern Formula 1 and allows teams to run programmes and improve their cars.
Mercedes have opted not to field a junior driver, with Lewis Hamilton set to drive on day one, with Valtteri Bottas taking over the seat on day two. This means that they will be able to run a non-F1 junior driver (most likely George Russell) for the second test in Hungary later in the year.
Regulations state that teams must run 'young drivers' - drivers that have competed in three or less Grand Prix - to run two of the four in-season days of testing.
Ferrari will be working with Pirelli in the test, as part of the tyre manufacturer's 2017 development programme. McLaren also announced their line-up, with Stoffel Vandoorne and Oliver Turvey set to drive.
Bahrain International Circuit - Winter testing