Jack Rodwell is facing two to three weeks out with a hamstring injury, manager David Moyes has revealed.
The Sunderland midfielder limped off during the second half of the 4-0 win over Crystal Palace last weekend and now faces a spell out injured.
The injury isn't as bad as first feared but it is enough to keep him out for the next few weeks.
There was brighter news for Adnan Januzaj and John O'Shea though after leaving the Selhurst Park field with hip and hamstring injuries, respectively.
Both have trained at the Academy of Light this week and should be available for selection.
Sunderland host Southampton at the Stadium of Light tomorrow (3pm KO) and the Black Cats could climb out of the relegation zone with a win.
Speaking at his pre-match press conference, Moyes said: "Januzaj and O'Shea have trained and hopefully they'll both be available.
"Jack Rodwell isn't available. It is not as bad as we first thought but it'll keep him out for a few weeks."