CARLTON midfielder Andrew Walker will miss the first half of the AFL season with a shoulder injury.

Walker will undergo surgery after injuring his right shoulder in Friday's practice match win over the Western Bulldogs at Princes Park.

The Blues said he would be sidelined for up to three months.

The 21-year-old, 74-game player had surgery on the same shoulder late last year, restricting his pre-season training.

Friday's practice match was only his second since coming back from that surgery.

Carlton play their opening game of the season against Richmond at the MCG next Thursday night.

Meanwhile, star recruit Chris Judd warned he was unlikely to hit top form until mid-season, after recovering from groin surgery.

The former West Coast premiership skipper played his first game in Carlton colours on Friday, a practice match against the Western Bulldogs.

"Realistically, the body's going to improve quite a bit over the next two or three months and it will be probably then that I'll be able to really go at 100 per cent," he told reporters at a club golf day.

"I haven't had the surgery before so I'm running in the dark a little bit as well.

"But from some of the other people I've spoken to, they didn't really feel like they reached full capacity until mid-year and realistically that's probably where I'll be as well."

Judd said he was surprised how rusty his form was in Friday's match.

"You quickly forget just how quick AFL football is, admittedly it was just a practice game, but you just can't replicate that in training," he said.