The team’s fortunes did not improve markedly in the afternoon when Bottas handed over testing duties to Hamilton, the pair curtailed to just 45 laps in total between them on day one of the three-day test.
And then Hamilton’s afternoon in the car ended abruptly when he come off the track after locking up his brakes in turn one when trying to record a fast lap. In the end, the Briton could only end the day 10th fastest
With testing time already limited – teams have just three full days with one-and-a-half days allocated per driver – it is a potentially sizeable setback for the dominant force of the sport in recent years.
Team boss Toto Wolff said of the day-one struggle: “It wasn’t a good start because we had a gearbox issue that came out of nowhere that we haven’t yet been ready to identify and understand.
“So I hope if we are able to have a smoother ride from here onwards, then I think we can recover. If we have more stumbling blocks, then obviously with three days there’s not a lot you can do.”
Mercedes were not the only car to suffer gremlins on day one with Mick Schumacher’s debut on track for Haas limited by a hydraulic issue.
On track, Kimi Raikkonen suffered an early lock-up, while Max Verstappen, tipped as the closest challenger to Mercedes this season, suffered a big spin but escaped without damage.
Verstappen, who completed 138 laps, set the pace on the opening day, parts of which saw the Sakhir Circuit covered by a sandstorm.