Tour de France winner Floyd Landis has undergone hip replacement surgery in California.
Landis could face a two-year ban after failing a drugs test
Landis broke his hip in a training accident three years ago and the injury had resulted in a deterioration of the joint and decreased blood flow.
The American was charged by the US Anti-Doping Agency (USADA) last week after testing positive for drugs during his Tour success earlier this year.
He denies all charges and has requested an arbitration hearing.
The American tested positive for unusual levels of testosterone after winning stage 17 of this year's Tour de France
Landis' medical team are confident he will make a full recovery from the operation and have said he can resume training in two weeks.
"The state-of-the-art replacement will maximize Landis' chance of returning to top-level competition," said a statement.