Mercedes have suffered from a mechanical issue on the second day of the Bahrain F1 pre-season test, with George Russell stopping on track.
With the team aiming to make up for lost time in the pit lane with a range of setup changes, Russell returned to the track with less than two hours of the day to go.
Taking part in a long run, Russell's car developed an issue at Turn 4, with the Mercedes car signalling "hydraulic failure" on the steering wheel at Turn 8.
With Russell downshifting, the car became stuck in fourth gear and, with the car eventually slowing to a stop on the inside of the left-hand Turn 10.
The team confirmed shortly after that Russell's car did suffer from a failure in the hydraulics system.
The issue brought out the first red flag in what had been a largely reliable day for most of the teams.