Stoner has now won six straight pole positions

Australian Casey Stoner will start on pole position for Sunday's Czech Grand Prix at Brno.

Stoner topped qualifying with a fastest time of two minutes 11.567 seconds to edge championship leader Valentino Rossi (2:12.846) into second.

American John Hopkins (2:12.959) was third, with Australia Chris Vermeulen fourth and Alex de Angelis in fifth.

Stoner has now won six straight poles, the longest streak since countryman Mick Doohan won 12 in a row in 1997.

Britain's James Toseland crashed midway through the rain-soaked session and failed to qualify along with Jorge Lorenzo of Spain.

Fifteen riders qualified for Sunday's race, the first since Rossi won the US Grand Prix on 20 July.

Ducati rider Stoner, who fell ill with fever and cramp during Friday's free practice, is the defending champion at Brno.

"The track condition was very difficult today," said Stoner.

Rossi leads the MotoGP championship standings with 212 points, ahead of Stoner with 187. Dani Pedrosa of Spain is third with 171 points.