St Kilda star Nick Riewoldt has revealed that his knee injury will most likely keep him sidelined for over a month.

Riewoldt injured his knee late in the Saints' loss to Melbourne on Saturday afternoon, with the club and fans all around the country fearing the worst for the club champion after his knee buckled.

However, scans revealed on Sunday the 34-year-old avoided a serious injury as there was no structural damage, with St Kilda breathing a huge sigh of relief.

But Riewoldt revealed on The Footy Show on Thursday night he will still miss between two to six weeks with a split knee joint capsule.

Riewoldt collected 14 disposals, grabbed seven marks and kicked four goals against the Demons before going down.