German international David Odonkor will be out for two months after undergoing an operation on his knee.
The injury means the Real Betis winger will miss Germany’s final Euro 2008 qualifiers against Cyprus and Wales, as well as a number of domestic fixtures.
Odonkor told Ruhr Nachrichten: “It looks like I’m going to be out for two months.
“The injury is a recurrence of an old problem – it’s not too serious, but I have to undergo an operation.”
Odonko moved to Real Betis in a £4million switch from Borussia Dortmund in August 2006.