Corey doubtful for Round 1

Geelong midfielder Joel Corey looks likely to miss the start of the AFL season after suffering a knee injury in Sunday's NAB Cup opener against North Melbourne.

Corey was subbed off at half-time of the Cats' 14-point loss to the Kangaroos after copping a knock to his knee.

Scans on Monday revealed that he suffered a slight tear to the lateral meniscus and he underwent surgery on Tuesday.

The injury is expected to keep the two-time premiership player on the sidelines for up to a month, but the Cats are optimistic he could be back sooner.

"Joel suffered a similar injury in 2005 and after the same procedure he returned after three weeks and we think this will be the same outcome," Cats football manager Neil Balme said on the club's official website.

"You never want an injury but in these cases it could always be worse. We are confident that Joel will be available early in the season."

Corey has played 199 matches and will become only the 26th Geelong player to reach 200 when he plays his next match.

The Cats play Richmond this weekend in Yea and open the 2010 season against Essendon at the MCG on March 26.