Richie McCaw is in doubt for the Crusaders' Super Rugby match against the Blues at Eden Park on Friday.

The All Blacks captain missed part of the Crusaders' training session on Monday as he nursed a tender calf after the 18-10 loss to the Chiefs at AMI Stadium last weekend. Ryan Crotty also missed training with a sore calf after the Chiefs game. Matt Todd will wear the No.7 jumper if McCaw is unavailable.

"We got dinged up, as [the Chiefs] did, so we are just taking a few days to recover," Crusaders assistant coach Tabai Matson said of the injuries.

Todd Blackadder had already conceded he had "a few selection headaches" ahead of the fixture on Friday, recognising his team must perform better than in their defeat by the Chiefs in Hamilton.

Tyler Bleydenaal is the player under most pressure after missing five penalty goals in the first half of the Crusaders' 18-10 loss in Christchurch, before he was replaced by Tom Taylor at the break. Blackadder, however, must decide whether to start Taylor or select former All Blacks fly-half Colin Slade in his first match since moving back from the Highlanders. Slade, who was not considered for the side to face the Chiefs because of a calf complaint, should be available for selection if he proves his fitness,

Centre Reynold Lee-Lo had a solid performance in Hamilton, but he may face the chop in order to shift Ryan Crotty to outside centre to allow All Blacks team-mate Taylor to start at No.12. The duo could straighten the attack and return the Crusaders to the form they saw last season, but that decision is moot if Crotty is unfit.

"Goal kicking aside, we still had enough opportunities in the score-zone," Blackadder told Fairfax New Zealand. "We were in the right part of the field but just didn't put on enough pressure because of individual errors. We just can't afford to let teams off the hook."

Elsewhere, Luke Whitelock will have to make way for the return of Kieran Read while George Whitelock may be sacked to get Todd in the starting XV if McCaw is fit.

Blackadder said that George Whitelock had a strong game before replacing him with Todd, who moved into the No.7 role while McCaw moved to the blindside; Blackadder said that he would consider that positional switch again if Todd were to start against the Blues.

"There's a few selection headaches that we have got because everyone is playing well," Blackadder said. "George, in the time he was out there, actually played really well. But certainly Matt Todd, when he came on, really made a huge impact. There will be some hard calls."