Collingwood star Alan Didak will lose a valuable chunk of his AFL pre-season, after tearing a leg muscle at training.

Didak, who turns 29 next week, will be sidelined for a month after scans revealed a torn adductor muscle, the Magpies said on Tuesday.

The forward-midfielder should be ready to play in Colllingwood’s opening home and away clash with Hawthorn on March 30.

But it is still a concern, given the veteran had a mediocre season by his standards last year, when he was also coming off an injury-interrupted pre-season.

The 202-gamer said the setback was particularly frustrating, as he had felt in excellent shape to improve on his 2011 form.

“I hit the ground running (at the Magpies’ training camp) in Arizona after not having the season I would have liked last year, and continued to do all the training after Christmas,” Didak told the club’s website.

“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 had a restricted pre-season last year, after surgery on a torn pectoral muscle, then was further hampered when he injured a calf muscle mid-season, which meant he missed five games.