McLaren's Jenson Button won a thrilling Hungarian Grand Prix that was won and lost on tyre strategy as the race was affected by intermittent wet weather.
Button fitted prime tyres at his third stop before the rain fell and he passed team-mate Lewis Hamilton for the lead.
Hamilton pitted six times, including a drive-through penalty, but passed Mark Webber's Red Bull to finish fourth.
Red Bull's championship leader Sebastian Vettel was second with Ferrari's Fernando Alonso third.
Button marked his 200th grand prix by recording his second win of the season at the Hungaroring, where he claimed his very first grand prix victory five years ago.
Remarkably, the 31-year-old Englishman is the only man to win an F1 race at the track in wet conditions - the only two races to have been hit by rain since the inaugural race in 1986.
"This is the first place where I won a grand prix, in 2006, in these sorts of conditions," said Button.
"I'm always lucky with these conditions. You are not always going to make the right call in these conditions but I feel I'm pretty good at making the right call when it comes to tyre choices - but I'm not the only one.
"We had good pace today and I was able to make the soft tyres last.
"The reason why we won today was because we were quick. If it didn't rain it wouldn't have made any difference."
Vettel recovered from some early mistakes to comfortably take second on a three-stop strategy and he now leads the championship by 83 points from team-mate Webber.
 | When you need a man with a cool head, Button is the man with a sixth sense BBC F1 commentator Martin Brundle |
"The start of the race I was struggling on inters and I tried to keep Lewis behind but it was important to move away from the pack behind," said Vettel.
"The second stint overall was a little bit better and the last stint I felt the pace was there, [but] I had some issues with the brakes.
"It was more important to bring the car home but all in all it's fair to say that Ferrari and McLaren on race pace in the last couple of events have made a step forwards."
Hamilton goes into the summer break third in the championship, 88 points behind Vettel, with Alonso one point back in fourth and Button remaining fifth, 100 points adrift.
Button had run behind Hamilton, who had passed Vettel for the lead, in the second phase of the race after jumping Vettel at the first round of stops.
But when Hamilton opted for the soft tyres at his third stop, Button followed the example set by Webber and chose the prime tyres.
That decision was crucial when the rain fell just over 20 laps later and the two McLaren drivers swapped the lead several times before Hamilton dived back to the pits for intermediate tyres and Button sailed off into the distance.
BBC F1 commentator Martin Brundle said: "When you need a man with a cool head, Button is the man with a sixth sense.
| ANDREW BENSON'S BLOG Vettel has not won for three races now, and there is no doubt, though, that Red Bull are slightly on the back foot, but still he left Hungary with a bigger championship lead than he had when he arrived. |
"Button brilliantly won the Hungarian GP. He was the class of the field but supreme steel was seen this afternoon as the drivers had to cope with extremely difficult conditions."
After a strong start, Hamilton threw his race away with the decision to fit soft tyres at his third stop.
His lead was already in jeopardy before the rain fell as both Red Bulls and Button had chosen the harder tyres and were aiming to get to the end of the race while Hamilton would have had to stop again.
When the rain came Hamilton at times struggled to control his McLaren and he made the decision to stop again for intermediate tyres. It was a decision team chief executive Jonathan Neale later said was down to the 2008 world champion.
As the wet weather faded away, Hamilton's decision proved to be the wrong one and he quickly returned to the pits to finish the race on prime tyres.
A drive-through penalty for rejoining in front of Paul di Resta's Force India after a spin put him behind Webber, but he was able to use his fresh tyres - with a little assistance from the congested midfield pack - to pass the Australian for fourth.
"Jenson was pushing me hard the whole race and the better man won today," said Hamilton.
"I was struggling a lot with the graining on my left front tyres. I don't know whether that was my fault by pushing too hard."
On the decision to change to intermediates tyres, Hamilton added: "It wasn't necessarily the best call, but that's motor racing. We can definitely say the team has done a fantastic job and for us to have been the most competitive cars this weekend means we go into the break in good spirits."
Alonso had chosen a similar strategy to Hamilton, also opting for the soft tyres on the third stop as he attempted to get past Webber, who had been holding him up since the first stops. But he quickly dived back to the pits for hard tyres as the rain fell and took third.
The Spaniard was satisfied with the result after finding himself overhauled by the two Mercedes' off the line and delayed in hunting down the Red Bulls by a slow second stop.
"This is good again for us," said the double world champion. "We expected hotter temperatures and more problems with degradation for our main competitors.
"It was difficult conditions for us but we reach another podium and that is a good target for each weekend."
| There was a small explosion on the left of the car. I never saw anything like that before Renault driver Nick Heidfeld |
Ferrari's Felipe Massa battled back from a difficult race to finish sixth behind Webber. The Brazilian was followed by Di Resta, who collected his first points for Force India since Malaysia.
Nico Rosberg, who found himself fourth on the opening lap, settled for ninth. His Mercedes team-mate Michael Schumacher retired after spinning off the track.
Toro Rosso celebrated their 100th grand prix with both drivers in the points. Sebastien Buemi finished eighth with Jaime Alguersuari 10th.
There was a dramatic moment when Nick Heidfeld's Renault caught fire coming out of the pit-lane, although the scary incident was not deemed dangerous enough to bring out the safety car.
An explosion after the German had climbed out of the car was caused by the engine's air bottle exploding.
The German explained: "The pit stop took longer than it should have and something overheated.
"I had a fire in Barcelona as well but this one got quite close and I felt some heat so I had to get out quickly. There was a small explosion on the left [of the car]. I never saw anything like that before."
