Sebastian Vettel has been handed a three-place grid penalty ahead of Sunday's United States Grand Prix.
The penalty, which further compromises his already fading hopes of securing the 2018 title, is the result of an incident in this morning's opening session.
In the wake of an incident which saw Charles Leclerc spin off into the gravel, the session was red flagged in order that gravel dumped on the track by the Monegasque driver could be cleared.
Vettel was subsequently summoned by the stewards who believed the Ferrari driver had not slowed sufficiently.
Shortly after the end of today's second session, having interviewed Vettel before it got underway, the stewards handed the German a three-place grid drop and two penalty points for his licence after finding that he did not slow sufficiently, a regulation breach deemed to be an "extremely serious matter".
The stewards, having viewed the relevant video evidence, positioning data and telemetry, and heard from a team representative, found that Vettel failed to stay above the minimum time set by the FIA ECU in marshalling sectors 6 and 7.
"As the regulation states, Art. 31.6 was added this year to ensure that drivers reduce speed significantly during a red flag," said the stewards. "A breach of this regulation is seen to be an extremely serious matter.
"To be consistent with previous decisions on similar incidents this year, the stewards assessed the penalty, which comes just two weeks after Esteban Ocon was penalised for a similar incident in Japan.
As a result of the penalty, Vettel can start no higher than fourth on the grid, assuming he takes pole position tomorrow, and with the German already trailing Lewis Hamilton by 67 points, this would appear to be the final nail in the four-time champion's hopes.
"I think that the stewards were very specific in saying that my slowing down time was 27.7 seconds," said Vettel in reaction to the penalty, "I saw the red flag, had a look around to see whether there was any car stuck in the wall between turn 9 and 10, and slowed down to comply with the rules.
"They found it was too long a time, but I can't do much about that. The rules are clear and we know them, but I think a situation like this happened just this time, in these weather conditions, and on the wet you would go slower anyway."