Mercedes driver Nico Rosberg controlled an incident-packed Monaco Grand Prix from start to finish, winning the event 30 years after his father Keke triumphed in the famous street race.
However, the race was clouded by a row that erupted over a secretive tyre test that Mercedes conducted with Pirelli after the previous race in Spain. The German squad's key rivals Red Bull and Ferrari have lodged a protest because Mercedes used its 2013 car for the tyre test, which they see as a contravention of the sporting regulations.
On track, Mercedes continued its impressive one-lap pace in qualifying and Rosberg and team-mate Lewis Hamilton shut-out the front row ahead of the Red Bulls of Sebastian Vettel and Mark Webber.
Come the race, Rosberg and Hamilton managed to hold first and second places into the opening right-hander, Sainte Devote, on the opening lap, with the Briton resisting fierce pressure from an eager Sebastian Vettel.
Further back McLaren twins Jenson Button and Sergio Perez almost came to blows, with the Mexican twice having to cut across corners in a bid to stay ahead of the 2009 world champion. His moves prompted Button to complain about his team-mate over the car-to-pit radio, and the team took the decision to tell Perez to cede position to Button.
The race remained static as the top runners conserved their tyres and the fact that the field remained very tightly bunched prompted most of the leading protagonists to switch from a planned two-stop to a one-stop strategy. Top ten runners Webber, Fernando Alonso, Kimi Räikkönen and Jenson Button had all made their stops when Ferrari's Felipe Massa had a massive accident at Sainte Devote, precipitating a safety car period. The Brazilian was shaken in the crash, which was very similar to one he had in practice on Saturday.