Valentino Rossi recorded his fourth win in a row at the Catalan MotoGP.

The Italian, who had been fourth on the starting grid, came in ahead of fellow Honda rider Tohru Ukawa of Japan and Spanish Yamaha rider Carlos Checa.

Rossi has now won five of the first six races in the 16-round championship.

Checa led the race after the first of the 25 laps but could not match the straight-line power of the Hondas and was overtaken by Rossi on lap 15.

Ukawa also overhauled the Spaniard soon after but could not improve on second.

In the 250cc class, Marco Melandri recorded his second victory in a row and closed the gap on championship leader Fonsi Nieto.

Italian Melandri led from start to finish in the 23-lap race and never looked in danger of being overtaken.

His compatriot Roberto Rolfo took second place after an absorbing battle with Spaniard Nieto, who finished third.

In the 125cc race, San Marino rider Manuel Poggiali edged out Spaniard Daniel Pedrosa by just 0.019 seconds

Leading times from Saturday's qualifying in Barcelona:

Moto GP:
1. Valentino Rossi (Italy) Honda 44 minutes 20.679 seconds
2. Tohru Ukawa (Japan) Honda 44:21.559
3. Carlos Checa (Spain) Yamaha 44:29.210
4. Max Biaggi (Italy) Yamaha 44:32.597
5. Alex Barros (Brazil) Honda 44:43.061
6. Loris Capirossi (Italy) Honda 44:50.775
7. Kenny Roberts (US) Suzuki 44:52.204
8. Daijiro Kato (Japan) Honda 44:54.591
9. Olivier Jacque (France) Yamaha 44:57.526
10. John Hopkins (U.S) Yamaha 45:12.259

250cc:
1. Marco Melandri (Italy) Aprilia 41:40.377
2. Roberto Rolfo ((Italy) Honda 41:42.570
3. Fonsi Nieto (Spain) Aprilia 41:43.066
4. Randy de Puniet (France) Aprilia 41:43.327
5. Franco Battaini (Italy) Aprilia 41:44.915
6. Casey Stoner (Australia) Aprilia 42:03.478
7. Naoki Matsudo (Japan) Yamaha 42:03.592
8. Shahrol Yuzy (Malaysia) Yamaha 42:03.751
9. Emilio Alzamora (Spain) Honda 42:04.963
10. Toni Elias (Spain) Aprilia 42:11.098

125cc:
1. Manuel Poggiali (San Marino) Gilera 41:18.211
2. Daniel Pedrosa (Spain) Honda 41:18.230
3. Steve Jenkner (Germany) Aprilia 41:28.099
4. Lucio Cecchinello (Italy) Aprilia 41:33.608
5. Simone Sanna (Italy) Aprilia 41:33.633
6. Joan Olive (Spain) Honda 41:33.697
7. Stefano Bianco (Italy) 41:33.760
8. Pablo Nieto (Spain) Aprilia 41:34.429
9. Mika Kallio (Finland) Honda 41:40.973
10. Mirko Giansanti (Italy) Honda 41:41.050