Jenson Button got the victory he wished for to mark his 200th grand prix start after finding himself in the right place at the right time as McLaren team-mate Lewis Hamilton's afternoon evaporated in a haze of pit visits.
The two Britons made contact through the opening corner of the 70-lap Hungarian Grand Prix, but it was Hamilton who appeared to have the upper hand as McLaren took control of the race in its early stages. Although Sebastian Vettel held on to his hard-earned qualifying advantage at the start, sprinting away from the pack as the lights went out, it was clear that the German did not have the right car for the damp conditions that greeted the field on Sunday morning.
After several side-by-side moments, Hamilton was finally able to force Vettel into an error reminiscent of the one he made in Canada, the Red Bull running wide through turn two and allowing its silver rival to open a valuable gap. The tricky conditions were catching more than the championship leader out, with RBR team-mate Mark Webber and, to a greater extreme, Sergio Perez losing places off the line, and Fernando Alonso also running wide in turn two, allowing the fast-starting Nico Rosberg to claim fourth.
Vettel's error also allowed Button to close in, but it took another ten laps before the 2006 Hungarian GP winner was able to follow his team-mate through. By then, Hamilton had opened out an advantage nearing eight seconds, while both Ferraris continued to search for grip, Alonso and Massa alternately spinning then making their way back through the field.
Hamilton led the field through the first round of stops, which came on lap ten as the conditions yielded enough of a dry line to render the intermediate Pirellis a poor alternative for the super-softs waiting in pit-lane. Webber was the first to take the plunge, with Massa following him in, and initially it appeared that the choice may have been made a lap or two early as both struggled for temperature. Button and several of the midfield pack followed a lap later, with the Briton also slithering out of pit-lane, before Hamilton, Vettel, Alonso and Rosberg following suit on lap twelve.
That allowed Michael Schumacher a brief spell at the head of the field, although the seven-time champion wasn't credited with leading the lap as he pitted next time around, and Hamilton held a 3.8secs cushion over Vettel when the order shook itself out. Button was past the points leader next time around but the gap had grown to nine seconds by the end of lap 20, despite beginning to report problems with his left front tyre.
The graining gradually allowed Button to close in, while Webber passed Alonso for fourth, almost threw it away again with a moment at turn one, and then set a new fastest lap in his effort to overcome the poor qualifying session which, with KERS and DRS problems, had left him sixth on the grid just a week after taking pole in Germany.
The Australian and his Spanish adversary were among the first to make their second stop for tyres, but not before Nick Heidfeld suffered a frightening moment as the Lotus Renault crew went to work. For the second time this season, the German had his car ignite underneath him, this time before his tyre change had been completed, but he calmly drove the car out of pit-lane before it caught properly alight. There was a further moment for one of the attending marshals as the engine grenaded through the bodywork as he attempted to quell the flames, but everyone eventually escaped unhurt.
While Webber and Alonso held position through their stops, Hamilton, Button and Vettel each cycled through the lead as they made the switch to another set of super-softs - despite Vettel having to avoid Heidfeld's stricken car which was being towed into the pit exit -but Mercedes hinted at the future face of the race by putting both Schumacher and Rosberg onto the harder prime tyre at their corresponding stops. The two silver arrows had been harder on their rubber than most, but the decision raised a few eyebrows with the race yet to reach halfway and the need to run both slick options negated by the intermediate-shod start.