Rochdale duo Chris Dagnall and Gary Brown face lengthy spells on the sidelines after being forced to undergo surgery.
Both players are unlikely to play again this season, according to Dale physio Andy Thorpe.
He told the club's official website: "Chris needs to have anterior cruciate reconstruction after which you'd usually be out for somewhere between six and nine months, so he's got a long road ahead.
"Gary's under the same surgeon but he's a bit more complicated having a posterior cruciate tear with other complications as well.
"This is not nearly as straightforward as an interior injury and has a more problematic situation where he will have the reconstruction done, but there would still be doubts even after nine months of rehab.
"He's a strong fit lad though and hopefully he can get through it."