McLaren's Daniel Ricciardo and Williams driver George Russell both saw their preparations for this weekend's Mexico City Grand Prix suffer from gearbox related issues on Friday.
Ricciardo was able to complete just seven initial laps in the hour-long afternoon session leaving him down in 15th place in the final timings.
"We’ve identified an issue on the Friday gearbox which we’re analysing in the garage," the team reported on Twitter at the time.
"We stopped him early after seeing some markers in the data, related to his gearbox, that we thought prudent to explore," added the team's executive director Andrea Stella later.
Russell was even less fortunate and wasn't able to set any representative time at all before being forced to pit his car at the end of just two laps of the Autódromo Hermanos Rodríguez.
The Briton was soon out of the car and back in his designer 'civvies', watching the rest of the afternoon's track activity from the pit wall.
"It was a gearbox failure so the guys are still looking into how it happened," he sighed. "There’s not a huge amount more to say to be honest.
"[We'll see] if we can recover that gearbox, and where we go from there really. Not ideal, but it’s only Friday, and point are rewarded on Sunday."
(Update: Williams has been forced to fit a new gearbox to Russell's car which implies a five-place grid penalty for the Briton)
There was a similar report from Ricciardo, whose McLaren uses the same Mercedes-manufactured gearbox as Williams. "Unfortunately, we didn’t really get much done this afternoon," the Australian said.
“We had an issue so we came in," he reported. "There [were] a few checks to go through, so we couldn’t get back out. Or let’s say, it wasn’t worth the risk going back out.
"I got a few laps in on the hard and then that was it. We have to get it all together tomorrow, but we will obviously have the morning session to get on top of it."
"These things happen, and we’ll just have to get into it [on Saturday]. We don’t have any time to waste so we’ll get amongst it. We’ve got a few challenges ahead but we’ll be alright."
“It’s definitely not written off yet,” he replied when asked if the afflicted gearbox could still be salvaged. "It obviously gives us a bit more work to do, but it’s definitely not out of reach."
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