Spain's Sete Gibernau has announced his retirement from MotoGP at the age of 33 after being dropped by Ducati next season in favour of Casey Stoner.
Gibernau was not a serious contender this season
Gibernau, who finished runner-up to Valentino Rossi in 2003 and 2004, said he had decided to quit despite being offered a ride with Kawasaki next year.
"It has been an incredible experience and has provided with me some unforgettable moments," he said.
His 2006 chances never recovered from a serious crash in Catalunya in June.
Gibernau said he would not feel right if he carried on racing after this season.
"If I had accepted the offers to continue just for the sake of carrying on then it wouldn't have made me happy especially if it was just for money," he said.
"Now I've got other projects to concentrate on."
In his top-class career, Gibernau raced for Yamaha, Suzuki, Honda and Ducati, winning his first Grand Prix in the last race of the 2001 season at Valencia.
In 2003, he claimed four wins and six other podium finishes to finish with the highest points total of any runner-up in the history of the top class.
But in recent years he slipped off the pace, only coming seventh in 2005 after a series of crashes and retirements, after which he left Honda for Ducati.
At Catalunya, he crashed and broke his hand and collarbone, injuries which kept him out of seven races.
He failed to get on the podium during the campaign and ended in 13th place in the championship.