George Russell will start Formula 1's United States Grand Prix from the pitlane as the result of a parc ferme rules breach by Mercedes.
The Briton had crashed out of Q3 at Austin on Saturday, badly damaging his W15 car after hitting the barriers at Turn 19.
The impact destroyed a new upgrade package that Mercedes had brought to this weekend's race, and left it with a dilemma about what to do as there are no spare parts available for the new developments.
Although Lewis Hamilton, who had qualified 19th after a miserable Q1, offered his upgrades to allow Russell to take up his sixth spot on the grid, this was deemed not practical by the team as that would have been too much work across both its cars.
Instead, the team knew that losing the upgrade meant it would likely have to revert Russell to the previous specification of car that had been used up until the Singapore GP.
The one saving grace of this happening in Austin is that it is without automatic penalty because teams are allowed to change specifications on sprint weekends if it is proven that there are no spares available.
However, even just focusing on Russell's car alone, to go back to the previous specification was too much effort to complete under normal parc ferme time limits – so the decision was taken to keep working overnight.
This meant that the normal parc ferme covers that are fitted to cars, to prevent any work taking place when it is in operation, were kept off. This is a breach of the rules and requires the driver to start from the pitlane.
A team statement said: "We had to work on the car overnight during the car's covered period.
"The workload involved in that was due to reverting on specification to what we ran in Singapore."
Russell's pitlane start means Mercedes faces a difficult time in the USA GP, with its drivers well down the order.
Hamilton will start 17th now, thanks to Russell dropping off the grid and RB's Liam Lawson having to start at the back because of an engine change penalty.
