LAGUNA SECA, California: Italy's Valentino Rossi stretched his lead atop the MotoGP standings Sunday with a triumph in the US Grand Prix.

The Yamaha rider, a seven-time world champion, emerged victorious after a fierce duel with reigning world champ Casey Stoner, who finished second aboard a Ducati, with Stoner's fellow Australian Chris Vermeulen third on a Suzuki.

Stoner, winner on the challenging, hilly Laguna Seca layout last year, had dominated all of the free practice and qualifying this week, and had won the last three races from pole position to thrust himself into the title picture.