Mercedes has triggered the second red flag of F1's Bahrain pre-season test after George Russell stopped on track.
The Briton pulled to the side of the road at the exit of turn 10 having been stuck in fourth gear throughout the middle sector.
Russell struggled to turn the steering wheel after a message was displayed on his dashboard, which read that there was a hydraulic failure. This could be a more sinister failure, or simply an erroneous sensor, which would be a quicker fix.
The issue could put an end to Mercedes' day with only 90 minutes left of the session, which represents a nightmare scenario for the German manufacturer.
READ MORE: Wolff reveals 'mentally difficult' Mercedes challenge
The late running provides more representative running under the floodlights which matches up with session timings for the Bahrain Grand Prix next weekend.
Mechanics recovering the car also face the unenviable task of attempting to cover up the entire car, including the floor underneath, to keep prying eyes away from spying on Mercedes solutions during the recovery process.
Felipe Drugovich triggered the only other red flag of the test so far for Aston Martin when stopping at turn four just nine minutes into the first day.
READ MORE: Mercedes confirm Russell hydraulic failure after red flag
Challenge for Mercedes
Russell's issue follows team principal Toto Wolff's concession that the winter period and beginning of track running was 'mentally difficult' following the struggles with the W13.
The Austrian explained: "Obviously, mentally it is always difficult to start with a car that was not on par last year and hopefully see something that is better," said Wolff.
"This is where the excitement comes from but equally, you want to get it right."
READ MORE: ’Change your f***ing car’ - Horner vs Wolff erupts on Drive To Survive
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