ST KILDA’S hopes of defending its 2008 NAB Cup win have been dealt a blow with skipper Nick Riewoldt ruled out of the pre-season competition after undergoing arthroscopic surgery on Friday night.

The forward spearhead had what the club described as a “routine procedure” after experiencing soreness in his left knee following training.

Recovery is expected to take four weeks, meaning Riewoldt should be fit to play in St Kilda’s opening match of the premiership season against the Swans on March 28 at Telstra Dome.

“This week during training Nick was experiencing some discomfort in his left knee,” said St Kilda Football Manager Greg Hutchison.

“The club and Nick decided the best option was to operate quickly and ensure he is in peak condition for this year.

“As a result of the arthroscopy Nick will miss the NAB Cup pre-season competition. However he is expected to complete a full recovery program with our strength and conditioning team … and be on track for the start of home-and-away season.”

Riewoldt has experienced problems with his knees in the past. A knock received against Richmond in round seven least year saw the inspirational Saint miss just one match, although it was initially feared he could be out for up to eight weeks.

Earlier in 2008, Riewoldt experienced tendonitis in his knee due to a badly corked thigh. The condition kept him out of pre-season action for two weeks and led to unfounded speculation that the captain was suffering from a more serious injury to his  anterior cruciate ligament.