Daniil Kvyat made two strong passes in the closing laps to finish fourth for Red Bull, ahead of Force India’s Sergio Perez, Williams’ Felipe Massa and Ferrari’s Kimi Raikkonen. A typically aggressive drive from Max Verstappen resulted in eighth place for Toro Rosso, with Williams’ Valtteri Bottas and Sauber’s Marcus Ericsson completing the top ten.
As expected, the new starting procedures mixed things up off the line, with Rosberg and Bottas making poor getaways from P2 and P3 on the grid, as Perez (starting P4) and Red Bull’s Daniel Ricciardo (P5) capitalised to chase polesitter Hamilton out of the first turn. Perez actually got ahead briefly on the Kemmel straight, but Hamilton had the inside line and reclaimed the lead under braking for Les Combes.
The Briton quickly pulled away and looked very comfortable, in part because Rosberg was stuck down the order. At the first round of stops the German was able to get back on terms with his team mate, and when the Virtual Safety Car was deployed on lap 21 to remove Ricciardo’s broken-down Red Bull the gap was barely two seconds.
From there, however, Hamilton had things in hand, managing the gap to claim a 39th Grand Prix triumph, and an 80th podium - putting him on level terms with Ayrton Senna in fourth in the all-time lists.
The real battles were happening behind - most notably in the fight for third. Grosjean was pushing Vettel hard in the closing stages, with the gap falling rapidly as the chequered flag neared. With one lap to run Grosjean was within DRS range, but the fight was settled early - and dramatically - when Vettel's right-rear tyre blew. Grosjean therefore scored his - and Lotus's - first podium since late 2013, much to their collective euphoria.
Behind, Kvyat made use of a late stop for soft tyres to charge through the order in the closing laps. He picked off Raikkonen on the Kemmel straight for seventh, and then scythed decisively past Massa and then Perez under braking for Les Combes.
Perez, Massa, Raikkonen and Verstappen almost tripped over each other as the quartet encountered Vettel's limping Ferrari, but eventually finished in order.
As good as Kvyat's moves were, the pass of the day arguably went to Verstappen after an extraordinary move around the outside of Ericsson at Blanchimont early on. The Dutchman was in feisty mood, and almost grabbed seventh late on - he out-braked Raikkonen at Les Combes, but was then caught out by Massa in front, causing him to almost spin and eventually surrender the position back to the Ferrari.
Bottas took a distant ninth in a race when Williams somehow contrived to fit three soft Pirelli tyres and one medium to his FW37 early on, earning him a drive-through penalty.
After a race-long fight, Ericsson led home Sauber team mate Felipe Nasr, as they comfortably outdistanced the uncompetitive McLarens of Fernando Alonso and Jenson Button. Down at Marussia, Roberto Merhi beat team mate Will Stevens for the final positions, 15th and 16th.
There were two early retirements: Force India’s Nico Hulkenberg had power issues on the grid, prompting a second formation lap, while Pastor Maldonado’s Lotus came to a halt on just his second tour of Spa. Carlos Sainz also had technical issues en route to the grid and made a delayed start from the pit lane. Two laps down, he ultimately pulled his Toro Rosso into the garage to retire on lap 36.
Even with Maldonado's retirement while running seventh, it was a hugely important afternoon for Lotus: Grosjean's podium lifted them above Force India and into fifth in the constructors' standings, 50 points to 49. Mercedes lead the way on 426, ahead of Ferrari on 242, Williams on 161 and Red Bull on 108.
In the drivers’ table, Hamilton has 227 points to Rosberg’s 199 and Vettel’s 160.