Sunderland midfielder Jan Kirchoff has been ruled out for the next three months following a knee operation.
The 26-year-old suffered cartilage damage in the second half of his team's 1-0 defeat to Chelsea last week and has since had an operation on the meniscus in his knee.
According to Sky Sports News, the German is not expected to return to action until the end of March, which will rule him out of a number of key fixtures for his Premier League club.
Kirchoff, who joined the Black Cats from Bayern Munich in January, had only recently returned to action after missing two months of the season with a hamstring problem, but will now not be seen in a Sunderland shirt until 2017.
Sunderland's fight to move out of the Premier League relegation zone will continue with a trip to Manchester United on December 26.
