Ducati's Casey Stoner saw off the challenge of Valentino Rossi to win the China Grand Prix and extend his MotoGP championship lead to 15 points.
Stoner celebrates his victory at the Shanghai International Circuit
The Australian took the lead from Rossi at the start of the second lap and his victory was assured when the Italian went wide around a corner on lap 16.
The 21-year-old finished the 22-lap race in 44 minutes 12.891 seconds, more than three seconds ahead of Rossi.
American John Hopkins finished third for Suzuki and his first podium finish.
Reigning world champion Nicky Hayden of the United States suffered a spectacular spin on the second lap, but recovered to finish 12th.
Stoner now tops the riders' standings with 86 points to Rossi's 71.
He said: "It was a very difficult race with a lot of pressure from Valentino behind.
"Then he made a mistake and I was able to hold on. It was another big day for us."
Rossi, who started from pole and managed to pass Stoner several times on corners before being pegged back on the straights, insisted he was satisfied with second place.
"I tried to attack him," said the 28-year-old. "I'm happy because this track was always going to be difficult for us and we have 20 points."
Last year's winner Dani Pedrosa of Spain won a duel for fourth place with fellow Honda rider Marco Melandri of Italy while Stoner's Italian team-mate Loris Capirossi was sixth on the other works Ducati.
Spain's Toni Elias, fourth in the championship at the start of the race, also had a day to forget, crashing out after a wild lunge up the inside on the first corner.
In the 250cc race, world champion Jorge Lorenzo of Spain blew away his rivals for his third victory of the season.
Lukas Pesek took the first victory for a Czech in the 58-year history of the 125cc category, with Britain's Bradley Smith back in eighth.
China Grand Prix MotoGP, Shanghai.
1 C Stoner (Aus) Ducati 44:12.891
2 V Rossi (It) Yamaha 44:15.927
3 J Hopkins (USA) Suzuki 44:19.554
4 D Pedrosa (Sp) Honda 44:26.981
5 M Melandri (Ita) Honda 44:30.167
6 L Capirossi (It) Ducati 44:39.147
7 C Vermeulen (Aus) Suzuki 44:39.482
8 R de Puniet (Fr) Kawasaki 44:39.916
9 Alex Hofmann (Ger) Ducati 44:40.999
10 C Checa (Sp) Honda 44:45.848
11 C Edwards (USA) Yamaha 44:47.944
12 N Hayden (USA) Honda 44:50.218
13 S Guintoli (Fr) Yamaha 45:03.596
14 A Barros (Brz) Ducati 45:08.155
15 K Roberts Jr. (USA) KR212V 45:10.627
Overall Standings (After 4 of 18 races)
1 C Stoner (Aus) Ducati 86 points
2 V Rossi (It) Yamaha 71pts
3 D Pedrosa (Sp) Honda 49pts
4 M Melandri (It) Honda 41pts
5 J Hopkins (USA) Suzuki 39pts
6 T Elias (Sp) Honda 35pts
7 C Edwards (USA) Yamaha 31pts
8 L Capirossi (It) Ducati 30pts
= N Hayden (USA) Honda 30pts
= C Vermeulen (Aus) Suzuki 30pts