Nicky Hayden won the Moto GP world title in 2006
Former MotoGP world champion Nicky Hayden will leave Honda at the end of the season to join the Ducati team.
The 27-year-old will team up alongside Casey Stoner at Ducati, replacing Marco Melandri, who is heading to Kawasaki.
American Hayden will take part in a Ducati test straight after the final MotoGP round of the season which takes place at Valencia on 26 October.
"We wish to thank Nicky for all he has achieved as a rider and a man," Honda Racing president Masumi Hamane said.
Hayden, who won the world title in 2006, said: "Winning the world championship was by far the highlight of my career so far.
"I'd just like to thank everyone, and the best way to thank them is to put up some results these last few races."
The Kentucky-born rider, who is currently eighth in the world championship, has had a difficult season, missing races after breaking his right heel in an extreme sports event in Los Angeles.
But he enjoyed his best result of the campaign on Sunday when he came second at Indianapolis for his first podium finish to the season.
Hamane said Hayden had been "much-loved" by the team.
"Nicky and Honda have shared much success and a few disappointing days, but in each case Nicky has always behaved cheerfully and has led the team in a positive way.
"His warm-hearted character has been much-loved by all who have worked with him."
Repsol Honda team manager Kazuhiko Yamano added: "Nicky is a racer, a tough man on track and always a gentleman with whom it has been a pleasure to work.
"We all wish Nicky good luck and success with his new challenge. He will be a fierce rival for our team in 2009."
Ducati Corse CEO Claudio Domenicali was pleased to welcome Hayden into the ranks and said: "We are certain that his never-say-die attitude, riding style and character will be great additions to our team in 2009.
"I would like to thank HRC for allowing Nicky to start testing our bike immediately after the Valencia Grand Prix.
"I would also like to thank Marco Melandri for his professionalism during a difficult year, which was below all our expectations."