Sevilla midfielder Piotr Trochowski is set to be sidelined for around eight months after undergoing knee surgery on Monday night.
The 28-year-old German international underwent a three-hour operation at the Vail Valley Medical Centre in the USA to repair damaged cartilage in his right knee.
Trochowski was injured during the first half of Sevilla's La Liga defeat by Barcelona three weeks ago.
A statement on the Sevilla website read: "The operation has gone as planned and, if there are no complications, the recovery period is estimated at around eight months."
Trochowski will remain under observation in Vail Valley for a month before returning to Spain to continue his recovery.