McLaren's Lewis Hamilton has been excluded from qualifying at the Spanish Grand Prix after stopping his car out on the track at the end of qualifying.
Hamilton qualified on pole but will start from the back of the grid.
He was told to stop because there was insufficient fuel in the car for him to get back to the pits and provide a sample, as required by the rules.
The stewards rejected McLaren's argument that not putting enough fuel in the car was "force majeure".
The F1 rules require the car to return to the pits with one litre of fuel on board - running less fuel gives a performance advantage.
Although in this case the advantage gained in no way accounted for Hamilton's 0.578-second advantage over second placed Pastor Maldonado of Williams, the stewards felt they had to penalise McLaren.
Their ruling said: "A team member had put an insufficient quantity of fuel into the car, thereby resulting in the car having to be stopped on the circuit in order to be able to provide the required amount for sampling purposes.
"As the amount of fuel put into the car is under the complete control of the competitor, the stewards cannot accept this as a case of force majeure."
A McLaren statement said: "We accept that the stewards did not agree with our interpretation of force majeure. Our aim is now to maximise the points we can score."
McLaren team principal Martin Whitmarsh had argued that the size of the margin was a reason for Hamilton to be allowed to keep his position.
"It was a massive margin by the situation within F1 at the moment and he undoubtedly deserves to be there," Whitmarsh said.
McLaren technical director Paddy Lowe later tweeted: "To all our fans: so sorry about this error. We are more gutted than anybody. An amazing performance by Lewis throughout Q, ruined."
Hamilton said: "Today's qualifying session was one of the best I've ever driven - the whole car was just rolling so smoothly - it felt fantastic.
"To hear that I'd been excluded from qualifying, was of course extremely disappointing.
"Looking ahead I think it's clear that it's going to be an incredibly tough race for us. Even so, as always, I'll never give up and I'll give it everything I've got. Whatever grid position I start a Grand Prix from, I'll always race my heart out."
The decision gives Venezuelan Maldonado the first pole position of his career, with Ferrari's Fernando Alonso promoted to second place.
The rules on fuel were changed by F1's governing body, the FIA, after a similar problem with Hamilton's car at the 2010 Canadian Grand Prix.