Lewis Hamilton took a dominant victory in the Italian Grand Prix to beat Sauber's Sergio Perez and Ferrari's Fernando Alonso.
From pole position, Hamilton lost the lead only briefly during the pit-stop period and was never seriously under threat.
Perez, who qualified 12th, took advantage of a different strategy and free choice of tyres at the start to climb through the field and pass Alonso with seven laps to go.
McLaren's Jenson Button and Red Bull's Sebastian Vettel both retired.
Alonso, who drove an excellent race to climb up from 10th on the grid, has consolidated his championship lead and is now 37 points ahead of Hamilton, who moved up from fifth to second.
Vettel's retirement, with his second alternator failure of the weekend, dropped him to fourth, two points behind Hamilton and one behind Lotus's Kimi Raikkonen.
Red Bull's Mark Webber, who retired after a troubled race, is fifth, 47 points behind Alonso, with Button sixth, 78 points adrift and realistically out of contention.
The race contained plenty of action and overtaking, and a moment of major controversy between title contenders Alonso and Vettel.
The German was given a drive-though penalty for forcing the Spaniard off the track in an incident reminiscent of a similar one involving the same drivers in last year's race.
Last year, the German passed the Ferrari driver around the outside of the 180mph Curva Grande with two wheels on the grass and felt Alonso had pushed a bit too far.
Alonso was not penalised for that incident, the stewards feeling he had left just enough room for Vettel and that the Red Bull driver had gone on to the grass when he did not need to.
In this year's incident, on lap 26 of the race, the roles were reversed and Alonso tried to pass Vettel on the outside.