On-loan midfielder Alexander Hleb could feature on Birmingham's bench after recovering from a hamstring injury.
The Barcelona playmaker suffered the knock in the match against Fulham on November 27 and has been able to train with the squad again. He is short of match practice, and manager Alex McLeish has said he will take the decision on whether to include him as late as possible.
Blues have no other new fitness worries. James McFadden is a long-term absentee with a knee injury.
Sir Alex Ferguson expects to have Nani available again after the winger missed the win over Sunderland with a hip complaint.
He is likely to be one of a number of changes made to the side, with Ferguson keen to keep all his players fresh.
Park Ji-sung has now left for his Asian Cup commitments with South Korea and Paul Scholes (groin) is also out, whilst there are also doubts over John O'Shea (calf) and Darren Fletcher, who was sent home from training on Christmas Day with a heavy cold.
Birmingham (from): Foster, Carr, Murphy, Bowyer, Johnson, Ridgewell, Larsson, Gardner, Hleb, Jerome, Ferguson, Doyle, Dann, Madera, Fahey, Zigic, Valles, Parnaby, Beausejour, O'Shea, Redmond, Jiranek, Phillips.
Man Utd (from): Van der Sar, Kuszczak, Rafael, Brown, Neville, O'Shea, Ferdinand, Vidic, Smalling, Evans, Evra, Fabio, Nani, Obertan, Carrick, Fletcher, Gibson, Anderson, Giggs, Bebe, Rooney, Berbatov, Macheda, Hernandez, Owen.