Roger Hayden replaces injured de Puniet

Hayden, the 27-year-old brother of former MotoGP world champion and Ducati rider Nicky, has competed sporadically in the World Superbike Championship for Team Pedercini Kawasaki this year.

Hayden is also expected to race an American Honda-backed Moto2 bike in the Indianapolis GP after the summer break.

The American had made his MotoGP debut also at Laguna Seca in 2007, when he raced a Kawasaki to finish in 10th position.

De Puniet sustained breaks to his right tibia and fibula in an accident which caused the German Grand Prix to be stopped on Sunday.

It remains unclear how long the Frenchman will be out of action for, but the severity of his injury suggest he is unlikely to back in time to race before the San Marino Grand Prix at Misano at the beginning of September.

American rider Hayden possesses strong local knowledge of Laguna Seca and won a race there during his AMA Supersport championship year in 2007.

The circuit is also synonymous with his brother Nicky, who scored an emotional first grand prix victory there in 2005 and followed it up with another in 2006.