The extent of Cameron Munster's knee injury is worse than first thought, with genuine concern the star half could miss the opening week of the NRL finals.

Munster was rested from the final game of the regular season on Friday night, which resulted in a big win for the Melbourne Storm over the Cronulla Sharks.

It was thought originally that it was simply being rested, with plenty of others joining Munster on the sidelines as the Storm wrapped up the minor premiership.

However, coach Craig Bellamy said in the post game that Munster was battling a knee problem without letting on too many details.

โ€œCameron Munster has a little problem with his knee at the moment,โ€ Bellamy said in his post match press conference.

โ€œWe think he will be OK, but we havenโ€™t really looked at tonight either."

It has now been revealed by The Sydney Morning Herald's Christian Nicolussi that he has an infection in a cut he sustained during the Round 24 shock loss to the Parramatta Eels.

NRL Physio said it is now down to how the wound recovers and infection settles. There is little doubt Munster will be named when teams drop for Week 1 of the finals on Tuesday afternoon, however, there is a chance he may be unable to play.

Making matters worse for the Storm is that they will play on Friday night, their qualifying final coming against the Manly Sea Eagles. That will rob Munster of extra recovery time, as well as others like Josh Addo-Carr, who has a hamstring injury, and both Tui Kamikamica and Brandon Smith who didn't finish the game against Cronulla with minor injuries.