When it ended 78 laps later the German was 9.2s ahead after a brave and persistent challenge from the Briton had finally faded after 65 laps when he got dirt in his left eye and lost most of that time while trying to fish it out in the slow corners.
That enabled Daniel Ricciardo, once more than 12s adrift, to close in dramatically at the end as Hamilton continue to struggle with his vision. As Rosberg reeled off the final laps to take his second consecutive triumph in the Principality, and to regain the world championship lead by four points, an unhappy Hamilton just kept the Australian’s Red Bull at bay by 0.4s after a scrap which enlivened the closing stages.
Behind them, a slow-burn race came alive with other late battles. On a day when Fernando Alonso could do no better than fourth in his Ferrari, Nico Hulkenberg had worked his way up to fifth place but found himself under increasingly serious attack. Having earlier overtaken Kevin Magnussen’s McLaren with a brave move at Portier, the German subsequently found the Dane in his mirrors. Then, after Magnussen reported an engine problem on the 73rd lap which enabled team mate Jenson Button to overtake him, Hulkenberg was forced to withstand pressure from the Briton. Button had earlier survived a first-lap tangle at Mirabeau which had pitched Sergio Perez’s Force India into retirement.
This was, unusually, a race of attrition. Pastor Maldonado’s Lotus was the first retirement, followed by Perez, then Sebastian Vettel fell from an early third place when his Red Bull stuck in first gear. Daniil Kvyat’s strong run ended in retirement as his Toro Rosso lost power, and Adrian Sutil crashed his Sauber braking for the chicane on the 25th lap, bringing out the safety car for the second time after its intervention early on while Perez’s car was cleared away.
Hamilton thought that Mercedes’ failure to bring him in for fresh tyres in the immediate aftermath of Sutil’s crash compromised his chances of getting by Rosberg, though Mercedes’ rule is that the better placed driver gets that call first. Mercedes stopped them both on the 26th, when there was a rash of stops by most of the leading runners.
During this second deployment Kimi Raikkonen’s race went wrong when he was tapped by one of the Marussia’s behind the safety car, and needed a second pit stop for tyres. That dropped the Ferrari driver from third to 13th. Later, fighting back to get on terms with the McLarens, he ran wide trying to go inside Magnussen at the hairpin on the 74th lap and the two tangled before getting underway again. Raikkonen was subsequently reprimanded for the incident. After another stop for fresh rubber and a new front wing he crossed the line 12th.
In between the two Ferraris, Button failed by a tenth to dislodge Hulkenberg from fifth after harrying him in the final laps, as Felipe Massa rescued seventh place for Williams after starting 16th. The Brazilian was one of the few not to stop on the 26th lap when the safety car was out and kept going on Pirelli’s supersoft tyres until the 45th lap. He dropped from fifth to 11th but battled back to seventh, within striking distance of Hulkenberg and Button.
A strong run by Jules Bianchi made up for one penalty when both Marussias were deemed to have been out of position on the grid, and with the attrition he scored Marussia’s first-ever points with eighth, but with a five-second penalty to be added post-race for taking that first penalty under the safety car, he fell back to ninth behind Romain Grosjean’s surviving Lotus which was only 1.4s adrift. Nevertheless, it was a great effort from the Banbury-based team.
Magnussen got going again after his incident with Raikkonen and nursed his McLaren home for the final point, to the disappointment of Caterham for whom Marcus Ericsson took 11th ahead of the recovering Raikkonen, and team mate Kamui Kobayashi. The Japanese driver was embroiled in a fight with the Finn until Raikkonen pitted for fresh supersofts with five laps to go, and was aggrieved when Bianchi had shouldered past him earlier on at Rascasse when, for a while, it seemed that Caterham might score a point. Kobayashi sustained some debilitating rear-end damage in the incident but managed to come home ahead of the second Marussia of Max Chilton who brought up the rear in 14th.
The other retirements included Esteban Gutierrez, who was fighting very hard for eighth place with Valtteri Bottas’s Williams when he tagged the barriers at Rascasse with his right-rear tyre and spun. Bottas’s own run ended soon after with an engine failure at the hairpin. Jean-Eric Vergne ran very strongly initially and was fighting with Magnussen for sixth when they pitted under the safety car on the 26th lap. Toro Rosso got him out just ahead of the McLaren but it was mighty close and the Dane had to brake very hard to avoid a collision. The stewards thought the same and gave him a drive through penalty for unsafe release. That dropped the Frenchman from sixth to 13th, and during his attempt to regain lost ground his engine cried enough.
Rosberg’s second victory of the season moved him back ahead in the title chase, with 122 points to Hamilton’s 118. Alonso remains third with 61, but Ricciardo vaults to fourth on 54 from Hulkenberg on 47 and Vettel on 45.
Mercedes’ fifth 1-2 of the season lifts them up to 240 points, with Red Bull next on 98 from Ferrari on 78, Force India on 67, Williams on 52 and McLaren on 51.