Mercedes F1 boss Toto Wolff says the gearbox issue that disrupted the team's morning session in Bahrain "came out of nowhere" and has yet to be accurately diagnosed by the German outfit.
Valtteri Bottas reported a transmission issue after a single installation lap on Friday morning, which forced Mercedes' crews to undertake a gearbox change on the W12, a process completed just 45 minutes before the end of the morning segment.
"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," Wolff explained.
"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."
Lewis Hamilton took over in the afternoon session but had only accumulated 16 laps in the first two hours of running, having also endured a lengthy pause in the team's garage.
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Mercedes' niggling issues contrasted with the trouble-free day enjoyed to that point by rival Red Bull, with Max Verstappen approaching the century mark in the first two hours of the afternoon, setting the fastest lap in the process.
Although the Brackley squad's start to testing was certainly sub-optimal, it was not a cause for concern for the championship winning outfit, at least not yet. But no doubt the team will have taken note and rekindled its focus accordingly.
As for the performance level among the field's front-runners, Wolff says the picture will remain "vague" at best this weekend at Sakhir
"I think we will see some kind of vague picture after the three days," Wolff said.
"Bahrain is representative, but these days are very gusty, the wind conditions change from one day to another. And of course, we don’t know the fuel loads, and there’s quite a difference in performance just missing it by 10kg.
"So vague picture, but on the first race weekend, in qualifying, we’re going to know once the flag drops, the bullshit stops."
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