Didak, 28, went down with the injury during the Magpies' intense pre-season program.
He said he was extremely disappointed to have been struck down with another untimely injury.
“I was having a good pre-season and feeling positive about 2012,” Didak told collingwoodfc.com.au.
“I hit the ground running in Arizona after not having the season I would’ve liked last year, and continued to do all the training after Christmas.
“It’s extremely frustrating and disappointing to be sidelined for a few weeks, but hopefully I can recover well, get back and play some good footy in the early part of the season."
Didak has played 202 games for the 'Pies and suffered through an injury-interrupted 2011 season.
Magpies football director Geoff Walsh said while Didak's injury was unfortunate, the club hoped he would be right to go for the start of the home-and-away season.
“Alan has torn his adductor muscle and will miss the next four weeks,” Walsh told collingwoodfc.com.au.
“He has had scans to confirm the injury and now will go through a rehab schedule to hopefully get him back and ready for Round 1 of the home and away season.”