Hamilton came in at the end of lap 18, and the stop wasn’t up to McLaren’s usual mega-swift standards due to a problem with one of the wheel guns. He lost more than a second, but when Grosjean came in a lap later, he made a slow getaway, meaning the Briton maintained his lead.
Grosjean switched to a used set of soft tyres, which proved competitive and enabled him to briefly edge closer to medium-shod Hamilton during the next stint. But the Briton’s more durable tyres enabled him to keep his rival at bay.
Vettel also chose the soft tyre for the second stint of the race, and closed in on third-placed Button, who was on medium rubber like his McLaren team-mate.
Button popped in for his second stop on lap 34 and his race took a turn for the worst. He came out behind seventh-placed Bruno Senna, which cost him a vital few seconds, and the team also switched him onto a three-stop strategy, a decision that would cost him a potential podium.
With Button out of the way, Vettel put in some stunningly fast laps in a bid to leapfrog the Englishman. The German came in at the end of lap 38, and successfully jumped Button, who was still stuck behind Senna’s Williams.
Grosjean came in on lap 39 for medium tyres, with the gap at less than a second between him and the leader. Hamilton came in a lap later and successfully retained his lead, and edged away from his rival.
But as the challenge from one Lotus faded, the other one picked up the slack. Kimi Räikkönen – who had made a slow start and grappled with a malfunctioning KERS - set some stunningly fast laps during a long stint in the middle of the race to leapfrog Vettel, Alonso and emerged from the pits alongside Grosjean as they charged into Turn One.
Räikkönen had the inside line and forcefully edged his team-mate on the kerbs and seized second place. It was Kimi at his inspired best, and he wasn’t done yet. When he emerged from the pits he was just 4.4secs behind Hamilton, with tyres that were five laps fresher. He sliced huge chunks from the McLaren driver’s advantage over the next few laps.
But as soon as Räikkönen got in the dirty air behind Hamilton’s car, he was unable to make enough headway to mount an attack on the leader.
His only chance of victory was if Hamilton chewed up his tyres, but the Briton drove smoothly and duly notched up his 19th career victory and his third at the Hungaroring circuit.
Vettel dived in for another new set of soft tyres with ten laps to go, but emerged still in fourth, just ahead of Alonso and Button. He tore huge chunks of time out of Grosjean’s 17sec advantage, but wasn’t quite able to get on terms with the Frenchman.
Ferrari’s Fernando Alonso finished fifth, a result that means he continues to lead the world championship as F1 heads into its summer break. The Spaniard is 20 points ahead of Mark Webber, with Vettel a further two points back and Hamilton now up to fourth in the standings.
Hungarian Grand Prix, round 11/20, 29 July
1 Lewis Hamilton (McLaren)
2 Kimi Räikkönen (Lotus)
3 Romain Grosjean (Lotus)
4 Sebastian Vettel (Red Bull)
5 Fernando Alonso (Ferrari)
6 Jenson Button (McLaren)
7 Bruno Senna (Williams)
8 Mark Webber (Red Bull)
9 Felipe Massa (Ferrari)
10 Nico Rosberg (Mercedes)