All Blacks flyhalf Dan Carter threw a scare into his camp on Thursday as he laboured with a calf strain ahead of Saturday’s second rugby Test against Wales.

Although Carter remained on the team sheet following a training session late in the day, the All Blacks selectors have taken the precaution of calling up Luke McAlister as cover if he does pull out.

Carter, who orchestrated New Zealand’s two victories in recent weeks, has been unable to shake off the strain since feeling the first twinge during last weekend’s 42-9 drubbing of Wales in the first Test.

But he remained confident he would be able to take his place in the side.

“The way it’s improved during the week is positive,” he said as the All Blacks trained in heavy rain and on a greasy surface.

If he is unable to take the field on Saturday, Test novice Aaron Cruden is expected to be thrust into the crucial flyhalf starting role with McAlister added to the bench.

Cruden’s only All Blacks appearances so far have been brief cameos as a late substitute for Carter against Ireland and Wales.

Carter, however, is pivotal to the All Blacks performance and after an indifferent Super 14 season, he has been in sublime form in the Tests.

He scored 27 points in the first Test against Wales to add to the 17 he scored in the 66-28 whipping of Ireland the previous week, and All Blacks backs coach Wayne Smith was left struggling for superlatives.

“Daniel. What do you say,” Smith enthused after the Wales Test.

“He’s got his running game back, his goal kicking is superb, his kicking in the second half was pinpoint, got us into the right areas and he’s a great defender on top of that. Is there anything I missed?”

All Blacks head coach Graham Henry, himself a former Wales coach, expressed a measure of satisfaction with his side in the first two Tests of the year but said there were still areas to improve upon before the Tri-Nations series starts next month.

“We certainly need to improve on the first-half performance. If we can put two halves together I’ll be happy,” he said.

“We’ve just got to be aware, to build better as a team and as individuals to start the game.”

Wales coach Warren Gatland has made two changes to his first Test side including the surprise move of promoting second-string flyhalf Dan Biggar over the 90-Test veteran Stephen Jones.

The other change sees Jonathan Davies replace injured centre Andrew Bishop while Jones joins halfback Richard Rees, winger Will Harries and prop Craig Mitchell as new faces on the bench.

Gatland said he had no concerns about fielding the 20-year-old Biggar, although he admitted that not everyone shared his enthusiasm for the player.

“We’ve known he’s a kid with a bit of talent. Back home there’s mixed views about Dan, a lot of people love him or hate him.”

Wales captain Ryan Jones said his Ospreys teammate did not lack for confidence and was not fazed about his mixed reviews.

“Dan doesn’t care in the slightest. He’s a great kid. I live down from him and share rides daily. He’s got a fantastic maturity for a young kid and he knows he’s got the talent.”

Gatland also believed the All Blacks would wait until the last minute before deciding whether to risk Carter against Biggar.

“We understand he (Carter) hasn’t trained for a couple of days… I think Graham will give Dan till Saturday before 5:00 pm before he makes that decision.”