Spielberg - Lewis Hamilton's hopes of reducing Sebastian Vettel's 14-points lead in this year's drivers' world championship suffered a setback late on Friday when he was handed a five-place grid penalty for this weekend's Austrian Grand Prix.
The penalty is the regulation mandatory punishment for an unscheduled gearbox change, in this case before Hamilton's unit had completed six races, his Mercedes team confirmed.
The matter was referred to the race stewards at the Red Bull Ring on Friday evening after the three-time world champion Briton had dominated both opening practice sessions.
In a statement, the sport's ruling body, the International Motoring Federation (FIA) said: "The above driver (Hamilton) did finish the last race in Baku and this gearbox change was before the six consecutive events expired.
"As this is not in compliance with Article 23.5a of the 2017 Formula One Sporting Regulations, I am referring this matter to the stewards for their consideration.
"The team informed the technical delegate about the gearbox change on Tuesday, July 4, 2017, at 11:29 hours.'"
The mandatory sanction is a five-place penalty, which means that even if Hamilton is fastest again in Saturday's qualifying he cannot start Sunday's race higher than sixth on the grid.
Mercedes said they had ruled out the possibility that the damage to Hamilton's car was done when four-time champion German Vettel of Ferrari twice drove into him during last month's Azerbaijan Grand Prix.
Hamilton's penalty is the latest unfortunate setback to his mounting championship challenge and follows his bad luck in Baku where, following Vettel's 'road rage' attack, his head-rest worked loose and cost him a near-certain victory.
It is sure to be a source of further aggravation, too, in a week when Vettel, on his 30th birthday on Monday, escaped further punishment for his reckless behaviour in Baku. He was given a 10-seconds stop-go penalty during the race, but that was rendered ineffective - in terms of the championship scrap with Hamilton - by the Englishman's head-rest problems.
Before learning of his latest misfortune, Hamilton told reporters how he was approaching the Austrian race.
He said: "I have been training, keeping my head down, staying focused and staying quiet and making sure I came here healthy and strong so we can fight.
"These two weekends are important. I lost points in the last race and I want to reverse that. These next two are an opportunity to do that."
He broke his own lap record twice on Friday in practice as he eased clear of the pack despite power problems that required a changed spark plug.
"It has been a pretty good day at the track, pretty good from the get-go," he said. "The track was amazing from the start so we had a good baseline to start with and have just been chipping away at it.
"I'm sure people don't even realise we still have spark plugs because these engines are so complex. There were some other things they were working on so it didn't particularly get rid of the issue that was there."
Vettel was nearly two-tenths down in second, but will harbour a strong belief that he can claim pole and end Mercedes' three-year dominance on the Austrian track in the Styrian Alps.