Former MotoGP world champion Nicky Hayden is to undergo shoulder surgery this week after a weakness was revealed in winter testing.
The Ducati rider left a recent pre-season event in Sepang early to head for medical tests in his native USA.
The scans revealed damage to cartilage in his left shoulder and muscles in his back.
"Of course another operation before the season is never a good thing", Hayden said.
"But I'm actually happy that I tried to ride at Malaysia because it helped me discover that the problem with the shoulder was bigger than we thought."
The latest news continues an injury-strewn previous few months for the 2006 title winner.
He broke his wrist in the Valencia Grand Prix in November and shattered two ribs and a shoulder blade during a training accident in Kentucky shortly after Christmas.
Hayden continued: "Setbacks are a part of life and a part of MotoGP, so we'll deal with it and do everything possible to get back on the bike in good condition as soon as possible."
The first race of the new season will take place at the desert circuit of Losail in Qatar on 8 April 2012.
