All Blacks and Crusaders Captain Richie McCaw has been ruled out for 5 weeks after sustaining a medical ligament strain in his team's 6-0 loss to the Highlanders on Sunday.

In further bad news for the defending champion, in form wing Jared Payne has also been ruled out for an undefined time period with a high ankle sprain which could even cost him the rest of the season.

Crusaders Coach Todd Blackadders is hopeful McCaw will make the team's 3 match tour of South Africa in April and said George Whitelock now has a crucial role to play.

Blackadder is hopeful a couple of injured backs will be available for Saturday's match against the Western Force in Christchurch.

Both Leon MacDonald and Kade Poki are 5-50 chances to return this week so they have got their fingers crossed.