Jenson Button took his second victory of the year by controlling a hectic, wet Chinese Grand Prix.
The reigning World Champion once again benefited from an early tire call, this time staying out on slicks in the rain while most pitted for intermediates, and showed his class again from the front. Even when a safety car period eradicated the lead his tire gamble had earned him, he kept his head in tricky conditions and even stretched away from McLaren teammate Lewis Hamilton in the closing stages when it came down to who had looked after their tires the best.
But far from being a race of nursing the cars home, for close to 90 minutes it was frantic stuff as the weather once again played havoc with Formula 1.
The drama started early when Vitantonio Liuzzi lost control of his Force India under braking, spun and collected the Toro Rosso of Sebastien Buemi and Kamui Kobayashi's Sauber.
Adrian Sutil, Jaime Alguersuari and Rubens Barrichello were also involved and headed for repairs in the pits, while Nico Hulkenberg did well to pick his way through unscathed.
But the safety car was still required, prompting both Red Bulls, both Ferraris, Hamilton and Michael Schumacher to gamble on changing to intermediate tires.
Initially, it looked like the right call as Fernando Alonso charged past cars still on slicks. But Nico Rosberg and Button, up front having stayed out on slicks, were lapping faster just one tour later as the inters cooked quickly with the circuit not quite wet enough for them.
Within a couple of laps all those to take them were back in the pits for slicks, leaving Rosberg, Button, Robert Kubica and Vitaly Petrov well ahead of the rest.
The stops included Hamilton and Sebastian Vettel racing each other into the pitlane and leaving side-by-side too, an incident that will be investigated later.
No sooner had the likes of Hamilton and Vettel fought their way back up the order that the rain started again, heavier this time. Leader Rosberg was caught out and a brief off-track excursion allowed Button a run at him to take the lead, and soon after everyone was in the pits to get inters back on.
The rain gifted Button, Rosberg and the Renaults a free pit stop, so the leaders 50-second advantage remained. But the safety car was back out after Alguersuari clipped the back of an HRT car and left front wing debris scattered on the track.
Button bunched the pack right up for the restart and, with the new rule about overtaking from the pitlane line, rather than the start/finish line, Vettel tried to take advantage to mug Hamilton into the last corner. But it backfired for his Red Bull team as he only succeeded in forcing Hamilton wide and shoving Webber off the track on the outside, costing the Aussie several places.
Hamilton once again had to make his way back to the front and his journey included a great battle with Schumacher. The old hand defended brilliantly for the first few advances, despite struggling for traction in his Mercedes. But eventually Hamilton made it stick with an opportunistic dive between Turns 8 and 9 - something that became his staple move of the day.
He then caught and passed Rosberg for second, just before the field descended on the pitlane once more for a final fresh set of intermediate tires.
Things eventually settled down for the last 20 laps, as Button kept Hamilton at a safe distance. There was just a brief scare four laps from home when he overshot the final hairpin. But Hamilton was also struggling to keep his car on the road with fast-balding inters.
Rosberg couldn't quite challenge for the victory but had no trouble keeping Fernando Alonso at bay for third - the Spaniard getting in reach of the podium despite five pit stops, including a drive-through for jumping the start.
Kubica continued Renault's good form, capitalizing on his early decision to stay on slicks to hold onto fifth. Vettel looked like homing in on Kubica in the closing stages but never threatened.
Webber had another day of missed opportunities and couldn't make his way forward at the same rate as Hamilton or Vettel, but he also had his share of misfortune. Already down the order he gambled on an earlier final stop, but it just left him in more tire trouble than most come the end of the race and he was passed for seventh by Petrov two laps from the end.
Some wise calls and excellent racecraft kept Schumacher in the hunt in spite of his lack of pace. But when the race finally settled down he had no answer and was relegated by Petrov, and then by his former Ferrari teammate Felipe Massa on the final lap, the latter once again failing to impress in a chaotic wet race.
PROVISIONAL RACE RESULTS
The Chinese Grand Prix
Shanghai International Circuit, China;
56 laps; 305.066km;
Weather: Mixed conditions.
Pos Driver Team Time
1. Button McLaren-Mercedes 1h44:42.163
2. Hamilton McLaren-Mercedes + 1.530
3. Rosberg Mercedes + 9.484
4. Alonso Ferrari + 11.869
5. Kubica Renault + 22.213
6. Vettel Red Bull-Renault + 33.310
7. Petrov Renault + 47.600
8. Webber Red Bull-Renault + 52.172
9. Massa Ferrari + 57.796
10. Schumacher Mercedes + 1:01.749
11. Sutil Force India-Mercedes + 1:02.874
12. Barrichello Williams-Cosworth + 1:03.665
13. Alguersuari Toro Rosso-Ferrari + 1:11.416
14. Kovalainen Lotus-Cosworth + 1 lap
15. Hulkenberg Williams-Cosworth + 1 lap
16. Senna HRT-Cosworth + 2 laps
17. Chandhok HRT-Cosworth + 4 laps
Fastest lap: Hamilton, 1:42.061
Driver Team On lap
Trulli Lotus-Cosworth 27
Di Grassi Virgin-Cosworth 9
De la Rosa Sauber-Ferrari 8
Buemi Toro Rosso-Ferrari 1
Kobayashi Sauber-Ferrari 1
Liuzzi Force India-Mercedes 1
Glock Virgin-Cosworth 1
World Championship standings, round 4:
1. Button 60 1. McLaren-Mercedes 109
2. Rosberg 50 2. Ferrari 90
3. Alonso 49 3. Red Bull-Renault 73
4. Hamilton 49 4. Mercedes 60
5. Vettel 45 5. Renault 46
6. Massa 41 6. Force India-Mercedes 18
7. Kubica 40 7. Williams-Cosworth 6
8. Webber 28 8. Toro Rosso-Ferrari 2
9. Sutil 10
10. Schumacher 10
11. Liuzzi 8
12. Petrov 6
13. Barrichello 5
14. Alguersuari 2
15. Hulkenberg 1
All timing unofficial