Mark Webber moved into the championship lead by dominating the Monaco Grand Prix from pole position and scoring his second victory in a week.
The Australian led home teammate Sebastian Vettel in a Red Bull one-two that put the duo equal at the head of the standings, but with Webber's back to back wins edging him ahead on countback. Front row starter Robert Kubica (Renault) had to settle for third.
Pre-race championship leader Jenson Button was an early retirement, but Fernando Alonso kept himself in contention by coming through from last to seventh.
The Red Bulls moved into formation off the line as Vettel immediately accelerated past front row starter Kubica into second. But any thoughts Vettel had of challenging his teammate for the lead were short-lived, as Webber started churning out fastest laps and established a 10sec lead by the time of their pit stops on laps 22 and 23.
Although the race was interrupted by no fewer than four safety car periods, the last of them covering the final three laps of the race, Webber was always able to rebuild his lead and pull away from Vettel, who was shadowed by Kubica all afternoon.
Felipe Massa (Ferrari) and Lewis Hamilton (McLaren) had quiet runs to finish where they had qualified in fourth and fifth, but it was a dreadful day for Hamilton's teammate Button, who fell to 11th at the start and then retired in a cloud of smoke while running behind the safety car. The team had accidentally left a blanking plate across the car's sidepod on the way to the grid, which Button suspected had caused overheating.
The early safety car was the lucky break Alonso needed after the practice crash that left him starting last. It was prompted when Williams's Nico Hulkenberg -- who had already dropped to the back with a clutch problem -- slammed into the wall in the tunnel on the opening lap, and while everyone else formed up behind the safety car, Alonso took advantage of a "free" pit stop and came in to switch to medium tires for the rest of the race. He then carved through the new team pack, despite determined resistance from Virgin's Lucas di Grassi in particular, and stayed close enough to the rest of the field to vault to sixth when all those ahead pitted.
Alonso looked set to finish there until the final yards of the race, when he got sideways out of Rascasse as the safety car came in to allow a final sprint to the line, and accidentally let Michael Schumacher slip through.
Schumacher got in front of Mercedes teammate Nico Rosberg at the start, although the fast-starting Rubens Barrichello was able to slip his Williams ahead of both as they battled. Despite Rosberg staying out until lap 28 on soft tires and setting several fastest laps, he was unable to get back ahead in the stops.
Stopping later worked for Adrian Sutil as he jumped past Force India teammate Tonio Liuzzi to take ninth as the duo gave the team its first double points finish. Barrichello lost ground in the pits and was running 10th until a problem at the left rear of his car caused him to crash at Massenet on lap 31, prompting the second caution. The third followed 12 laps later while a suspected loose drain cover at the same location was swiftly checked.
All the new teams' cars retired, the last of them when Lotus's Jarno Trulli, who had been delayed by a slow pit stop, vaulted over Hispania's Karun Chandhok at Rascasse near the finish. The crash, which happened right in front of leader Webber, prompted the final safety car. Heikki Kovalainen had comfortably led the group of new cars until gearbox problems on his Lotus.
Both Saubers dropped out early too, in Kamui Kobayashi's case while running fifth having stayed out on medium tires and moved up as others pitted.
PROVISIONAL RACE RESULTS
The Monaco Grand Prix
Monte Carlo, Monaco, Monaco;
78 laps; 260.520km;
Pos Driver Team Time
1. Webber Red Bull-Renault 1h50:00.000
2. Vettel Red Bull-Renault + 0.448
3. Kubica Renault + 1.600
4. Massa Ferrari + 2.600
5. Hamilton McLaren-Mercedes + 4.300
6. Schumacher Mercedes + 5.700
7. Alonso Ferrari + 6.300
8. Rosberg Mercedes + 6.600
9. Sutil Force India-Mercedes + 6.900
10. Liuzzi Force India-Mercedes + 7.300
11. Buemi Toro Rosso-Ferrari + 8.100
12. Alguersuari Toro Rosso-Ferrari + 9.100
13. Petrov Renault + 4 laps
Fastest lap: Vettel, 1:15.192
Driver Team On lap
Chandhok HRT-Cosworth 71
Trulli Lotus-Cosworth 71
Kovalainen Lotus-Cosworth 59
Senna HRT-Cosworth 59
Barrichello Williams-Cosworth 28
Kobayashi Sauber-Ferrari 27
Di Grassi Virgin-Cosworth 26
Glock Virgin-Cosworth 23
De la Rosa Sauber-Ferrari 22
Button McLaren-Mercedes 3
Hulkenberg Williams-Cosworth 1
World Championship standings, round 6:
1. Webber 78 1. Red Bull-Renault 156
2. Vettel 78 2. Ferrari 134
3. Alonso 73 3. McLaren-Mercedes 129
4. Button 70 4. Mercedes 84
5. Massa 61 5. Renault 65
6. Hamilton 59 6. Force India-Mercedes 27
7. Kubica 59 7. Williams-Cosworth 8
8. Rosberg 54 8. Toro Rosso-Ferrari 3
9. Schumacher 30
10. Sutil 18
11. Liuzzi 9
12. Barrichello 7
13. Petrov 6
14. Alguersuari 3
15. Hulkenberg 1
All timing unofficial