Lewis Hamilton was denied victory in the Monaco Grand Prix because of a strategic error by his Mercedes team, handing Nico Rosberg the win.
Hamilton controlled the race until Mercedes pitted him after a late safety car following Max Verstappen's crash.
Team-mate Nico Rosberg and Ferrari's Sebastian Vettel did not stop and passed Hamilton before he rejoined.
"We've lost this, haven't we?" Hamilton said to the team, correctly, before he was unable to regain the positions.
The result cuts Hamilton's advantage in the championship over Rosberg to 10 points, with Vettel a further 18 points adrift.
After crossing the finish line, Hamilton slowed to a stop at the Portier corner - which faces out to the Mediterranean Sea - seemingly to gather his thoughts.
He then completed the lap and drew up to the podium, where he knocked over his 'third place' parking board with the front of his Mercedes.
"I'm sorry about that, Lewis," his engineer Peter Bonnington said to him over the radio. "I'll have to have a word with the pit wall."
Rosberg said after the race: "Lewis drove brilliantly and deserved to win for sure, but that's the way it is in racing."
It was a bitter blow to Hamilton, who had come to Monaco determined to take his first win here since 2008 and had dominated the weekend.
The race was restarted with eight laps to go, with Hamilton on fresh tyres, but Monaco lived up to its reputation as a track where overtaking is all but impossible.
The closing laps were reminiscent of those in 1992, when McLaren's Ayrton Senna on old tyres managed to hold off the much faster Williams of Nigel Mansell after a late pit stop for the Englishman.
Like Mansell, Hamilton had a huge pace advantage but, like Senna, Vettel positioned his car perfectly to hold him off.
"I can't really express how I feel so I won't even attempt to," said Hamilton.
"This is a race that has been very close to my heart for many years. It was a great feeling to have that gap in the race. I didn't even have to push that much, I could have had double that lead if I had pushed. You live to fight another day.
"I'm sure we will sit down afterwards and try to think of ways we can improve. I'll come back to win the next one."
Amid an awkward atmosphere on the podium, Ferrari's Sebastian Vettel cheekily declared he was "very happy" with his second place.
Red Bull's Daniel Ricciardo did pull off a pass, taking fifth from Ferrari's Kimi Raikkonen on lap 72 with a controversial move that involved contact from Ricciardo's front wheel on Raikkonen's rear, which effectively shoved the Ferrari out of the way.
Red Bull ordered the Australian's team-mate Daniil Kvyat to let Ricciardo by into fourth place straight afterwards so he could challenge Hamilton for a place on the podium.
But, just as Hamilton could not pass Vettel, so Ricciardo was stuck behind the Mercedes and he was ordered to give fourth place back to Kvyat on the last lap.
The incident that led to the late-race drama was caused by a mistake by Verstappen as he tried to pass Lotus's Romain Grosjean for 10th place.
The 17-year-old Dutchman had impressed earlier in the race with some improvisational passing moves, including one on Williams's Valtteri Bottas which he pulled off by following Vettel through as he lapped the Finn.
But he misjudged an overtaking manoeuvre on Grosjean, smashed into the rear of the Lotus and was launched head on into the barriers at Sainte Devote, without injury.
A frustrated Raikkonen took sixth, ahead of Force India's Sergio Perez and Jenson Button, who scored McLaren's first points of the year in eighth.
Team-mate Fernando Alonso was on course to follow Button home, despite a five-second penalty for a collision with Force India's Nico Hulkenberg on the opening lap, but retired with a gearbox failure on lap 42.
The Spaniard's retirement promoted Sauber's Felipe Nasr to ninth ahead of Toro Rosso's Carlos Sainz.