Defender Simon Ramsden will miss the next month of Rochdale's League Two campaign.
Ramsden suffered a calf strain during Dale's 3-1 win at Accrington on Sunday and is now facing a lengthy spell on the sidelines.
"It will be at least a month before he is anywhere near ready," said Dale physio Andy Thorpe.
"He doesn't require a scan at this stage. With injuries like Simon's you have a general idea of the problem and can treat it accordingly."
Ramsden, 26, has been a regular for Rochdale since signing from Grimsby in January, 2006.