A wheel nut problem caused Sebastian Vettel to stop on track during the second practice session for the Bahrain Grand Prix, according to Ferrari.
Vettel reported that he lost drive coming out of Turn 4 on the sixth lap of a soft-tyre run in FP2, but after the session Ferrari said blamed the stoppage on "a problem with a wheel". Speaking to the press immediately after the session, Vettel was in the dark over the issue but confirmed the car lost drive.
"We don't know 100%," he said. "I felt out of turn four that I lost drive so I decided to stop. Obviously we don't want to risk or damage the car, which is a shame because I wanted to do a couple of more laps but that is what it is.
"Nowadays it is important to make sure you don't risk anything, the engine, the car as much as possible."
Ferrari was over 1.4s off the pace of Mercedes on Friday after Vettel made a mistake on his fast lap on super-soft tyres. Nevertheless, he is still confident his team can challenge Mercedes this weekend.
"We hope so, I think we could be a bit closer here. It is difficult to say, I don't know what Mercedes did today. They will be the ones to beat so we will push hard. A lot of homework today for us but I think we can improve.
"Mercedes is the benchmark, very fast this afternoon and this evening, they are the ones to beat. I think we can be closer, the car feels alright I think there are bits and bobs we can improve."