Mears began as a Man City trainee before joining Preston

The 24-year-old, who signed from West Ham last year, has been playing through the pain barrier in recent matches.

"He's got a nasty lump on his left shin and it's gradually got worse," Rams boss Paul Jewell told BBC Radio Derby.

"We got to the stage where he had to get the bit of stress fracture that hadn't healed scanned, and him out for eight to 12 weeks is a major blow."