Troy Bayliss (Ducati Xerox) powered to his second double of the year with two convincing wins at the Assen TT Circuit in the Netherlands in the fourth round of the HANNspree FIM Superbike World Championship front of 75,000 spectators. Bayliss powered to his fifth win at Assen in the opening race after a mistake by early leader Kagayama (Alstare Suzuki) on lap 12 left him with a gap at the chicane. The Australian then increased his lead over the following riders in the final laps to win by a margin of 2 seconds. Carlos Checa (Hannspree Ten Kate Honda) took the runner-up slot, in a sprint to the finish with Max Neukirchner (Suzuki Alstare). Kagayama took fourth from Troy Corser (Yamaha Motor Italia WSB), both riders holding off a late charge by Jakub Smrz (Ducati Guandalini).