Spain's Dani Pedrosa claimed the 50th Grand Prix win of his career on Sunday, taking victory in the Japanese MotoGP as runner-up Valentino Rossi extended his lead in the championship standings.

Pedrosa, who almost quit the sport earlier this year because of an arm problem that needed surgery, grabbed the lead seven laps from the end of a wet race at the Twin Ring ­circuit in Motegi.

He surged clear of his ­rivals to win for the first time this ­season and the 50th of his ­career, which began in the 125cc class in 2001.

Rossi finished second while his Yamaha teammate and championship rival Jorge Lorenzo faded to third after ­leading for most of the race ­until he had dropped back when having tire problems.

Rossi now leads Lorenzo by 18 points in the standings with a maximum of 75 available from the remaining three rounds, in Australia, Malaysia and Valencia.

Pedrosa had not won a ­MotoGP race since the Czech Grand Prix in August 2014 and missed three of the season's first four races due to the arm surgery.

The 30-year-old has suffered from a problem common among motorcycle racers when pressure builds up in the ­forearm and causes intense pain, making riding a bike difficult when the muscle becomes too big for the "sack" that it sits in.

Sunday's race was delayed by heavy morning rain which forced organizers to shorten the Moto2 and Moto3 races but Lorenzo was all smiles at the end of a long day.

"I kept my rhythm while the others burned their tire," he said. "At the end my pace was faster and I'm really happy."