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Lewis Hamilton was stripped of a thrilling Belgian Grand Prix victory on Sunday in a decision that slashed the McLaren driver's Formula One lead over Ferrari's Felipe Massa to just two points.
Hours after the jubilant Briton had sprayed the winner's champagne on the podium, stewards ruled he had gained an advantage from cutting a chicane in an all-or-nothing duel with Ferrari's Kimi Raikkonen three laps from the end.
Hamilton was given a retrospective drive-through penalty, a controversial decision which translated into 25 seconds added to his race time.
That was enough to demote the 23-year-old to third place, with main title rival Massa taking his fifth victory of the season and Germany's Nick Heidfeld promoted to a surprise second for BMW-Sauber.
McLaren announced their intention to appeal, although it was not immediately clear whether it would be allowed under the sport's regulations.
A spokesman for the governing International Automobile Federation (FIA) said it would be up to the sport's International Court of Appeal to decide at a later date.
With five races remaining, and Ferrari's home Italian Grand Prix at Monza next up, Hamilton has 76 points to Massa's 74 with BMW-Sauber's Polish driver Robert Kubica third on 58.
World champion Raikkonen, who crashed out on the penultimate lap, slipped to fourth on 57 points with his title hopes as dented as his car.
Ferrari meanwhile stretched their lead over McLaren in the constructors' standings to 12 points.
RAIKKONEN CRASHES
"I have often said that the race is not over until the official results are published and that was the case today," said Ferrari team principal Stefano Domenicali.
"This result is obviously very important for our championship hopes."
The stewards' enquiry overshadowed what had been one of Hamilton's best races with his most sensational finish of the season, and many disagreed with the outcome.
"I don't think Hamilton did anything wrong," said Niki Lauda, a former world champion for both Ferrari and McLaren. "He was going on the outside, he let him (Raikkonen) by...and afterwards he passed him."
Raikkonen, winner of the last three Belgian Grands Prix and chasing his first victory since April, had led from the second lap but Hamilton reeled him in as the skies opened and caused chaos two laps from the end.
Hamilton tried to pass at the Bus Stop chicane, went wide and allowed Raikkonen to get momentarily ahead on the straight before making a clean pass into La Source.
The Briton then slid at the top of the hill, allowing Raikkonen back in front before the Finn in turn slid and handed back the lead. The Finn then spun, narrowly missing traffic and crashing into the barriers.
"It was an experience and a half," said Hamilton before the stewards gave their verdict. "It was just mix and match. I was just praying for rain. I wanted it to come because I knew how to deal with it.
"It was one of the most exciting races of my career. I love having battles...I was on every limit that I knew possible, and even beyond."
The Briton was not available for comment afterwards and nor were team bosses.
Renault's double world champion Fernando Alonso was fourth, despite pitting for wet tyres on the penultimate lap, with Germany's Sebastian Vettel fifth for Toro Rosso and Kubica sixth.
France's Sebastien Bourdais considerably enhanced his prospects of staying at Toro Rosso next season with seventh while Mark Webber of Australia took the final point for Red Bull after Germany's Timo Glock also picked up a 25-second penalty for overtaking under a yellow warning flag.
McLaren's Heikki Kovalainen, who had started in third place, failed to finish but was listed as 10th after an error-strewn day that also included a drive-through penalty.