Millwall are hopeful winger Chris Hackett will be fit by the end of the month.
Hackett had only just returned from a groin strain when he aggravated a hip injury during Saturday's 1-0 home defeat by Sheffield United.
The 27-year-old has been ruled out of this weekend's trip to Middlesbrough but should not be sidelined for too long.
"Chris upset his hip joint causing him to be removed. He should return to training by the end of this month," said physio Bobby Bacic.