American Nicky Hayden boosted his championship hopes with a second straight US Grand Prix victory last night while Valentino Rossi's bid for a sixth MotoGP crown suffered a big blow.
Hayden, who earned his maiden career win on the Laguna Seca circuit last year, sat in behind pole sitter Chris Vermeulen early in the race until passing the Australian on lap 16 before charging home 3.18 seconds ahead of Honda team mate Dani Pedrosa. Italy's Marco Melandri, racing with a broken collarbone, was third, also on a Honda.
Five-times 500cc champion Rossi started well from back in 10th position after another disappointing qualifying effort but quickly worked up to sixth midway through the 32-lap race. But with three laps remaining, blue smoke began pouring from the back of the Italian's Yamaha, leaving him out of the points.
Hayden's second victory of the season gives the American 194 points and a 34-point lead over Pedrosa with six races left.
Rossi, who had arrived in California trailing Hayden by 26 points but riding the momentum of victory at the German Grand Prix, slipped to fourth with 143 points behind Melandri on 150.
Yukio Kagayama won both races of the World Superbike Championship round in the Czech Republic yesterday afternoon as the series leader, Troy Bayliss, suffered a setback.
The Japanese rider took both race victories in Brno for Corona Alstare Suzuki as Bayliss crashed out of race one and finished eighth second time out on his Ducati Xerox machine. Bayliss still holds a healthy lead in the championship but the fight for second is now between Japan's Noriyuki Haga, Britain's James Toseland and the Australian Troy Corser.
Toseland was second in race one on the Winston Ten Kate Honda but was fifth in race two. Haga backed up fourth in race one with third in race two and now has 189 points to Bayliss' 262, with Toseland third on 188 and Corser fourth on 173.
Elsewhere, Japan's Ryuichi Kiyonari won both races in the ninth round of the British Superbike Championship at Oulton Park, and leads the championship with 274 points.