Ronnie Stam and Franco Di Santo also suffered knocks in the 2-1 win over Preston but are expected to be fit while Victor Moses, who made his comeback from an ankle injury last weekend, is also pushing for a place in the squad.
Cup casualty: Thomas (right) will be unavailable against Birmingham
Club captain Gary Caldwell (hip) played in a behind-closed-doors friendly this week but is still a few weeks away from a first-team return while Tom Cleverley (knee) is also out.
Provisional squad: Al Habsi, Kirkland, Gohouri, Boyce, Stam, Figueroa, Alcaraz, N'Zogbia, Watson, Diame, Moses, McCarthy, Rodallega, Di Santo, Boselli, Gomez, S Caldwell, Golobart, McArthur.
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