Injured All Blacks fullback Mils Muliaina will have to pass a fitness test at Friday's Captain's Run to prove his readiness for a start in Saturday night's test against England at Eden Park.

Coach Graham Henry confirmed on Friday morning when he faced the media that there had still been no decision made around Muliaina's tweaked hamstring that prevented him training fully with the New Zealanders in the leadup to the Iveco Series test.

Muliaina injured his hamstring at Wednesday's training session, and was unable to take a full part in Thursday's preparations. Highlanders fullback and wider training group squad member Paul Williams was called in as cover.

"Mils will be fitness tested this morning," said Henry at his Friday Captain's Run press conference.

"No decision has been made yet," added the All Blacks coach, confirming that Williams would come on to the bench and Leon MacDonald would start in the No 15 jersey if Muliaina was unable to prove his fitness.

Henry also said he was confident if the late switch had to be made that it "won't change anything" in terms of the All Blacks' ability to implement their game plan.

Henry said if Williams had to take his spot on the bench he was confident the son of All Black legend Bryan Williams would respond to the challenge.

"Paul was with us in camp two weeks ago. He's filled in easily. He's a pretty mature guy who has played a lot of rugby at the level below. He's got a good feel about what's required. I'm sure he's thought about it and I'm sure his father has been helpful," added Henry.

Henry said apart from the scare around Muliaina, the All Blacks had otherwise had a "sound" week as they prepared for a match they were fairly certain would present a formidable challenge.

"There's a good feel in the camp. We know we've got a major contest on. We've done a bit of homework and those people who know the England team particularly well are very upbeat about the qualities of the side playing.

"We understand that it's going to be a major contest."

Whether Muliaina is going to be part of it is expected to be decided by early afternoon Friday, once the coaches and medical staff have had a chance to take in the assessment from his fitness test at the Captain's Run.