Bojan is to be assessed after coming off due to a back problem in the 1-0 Boxing Day win at Everton.
While the head injury sustained by Ryan Shawcross in that game should not stop him from being involved, Phil Bardsley is a doubt because of the ankle issue that ruled him out of playing at Goodison Park, and Stephen Ireland (knee) looks set to be absent again.
West Brom midfielder Graham Dorrans could return for Sunday’s Barclays Premier League trip to Stoke after missing the Boxing Day loss to Manchester City through illness and a calf strain.
Captain Chris Brunt might also be pushing for a start after making his comeback from a hamstring injury as a substitute against City.
Striker Victor Anichebe (groin) remains on the sidelines but fellow forward Georgios Samaras, who did not feature on Friday, is available again after returning home for family reasons.