Centre-back Mills picked up his fifth booking of the season in Saturday`s 1-1 draw at Watford and will serve an automatic one-match ban with Zurab Khizanishvili is likely to take his place.
On-loan midfielder Mikele Leigertwood is expected to make his debut after signing from QPR on Monday on a deal until January.
Defender Ian Harte is fit to face his former club after overcoming a trapped nerve which caused him to be replaced at half-time against the Hornets. Midfielder Jay Tabb also came off last weekend with a dead leg but he has recovered in time to face the Whites.
Club captain Ivar Ingimarsson remains a long-term absentee with a hamstring problem as does central midfielder Brynjar Gunnarsson who continues to struggle with a thigh problem.
Striker Noel Hunt will be hoping to continue his good form following his 15 months out through injury having netted three goals in the Royals last three games.
Source: PA
Source: PA