It's an enticing prospect, leading New Zealand in a potentially series-winning game against their arch rivals, but Casey Williams insists she will not resume her international career against Australia on Thursday unless confident she will not let her side down.

The opening test of the annual Constellation Cup series in Melbourne yesterday was meant to herald the inspirational defender's return to Silver Ferns duty after a 14-month lay-off but a knee injury instead forced her to witness New Zealand's 54-52 victory from the bench inside Hisense Arena.

A knock to her left knee during the final training session ruled her out and although it is not considered serious, the 64-cap veteran agreed with coaching and medical staff that she should not risk damaging the joint further given the Ferns busy upcoming schedule.

Williams sat courtside as a combination of advisor, timekeeper and cheerleader and despite being frustrated she was prepared to stay on the periphery at Auckland's Vector Arena.

Naturally Williams wants to return to the heart of a Ferns defence that produced a nerve-soothing performance in game one but like coach Wai Taumaunu she was adopting a cautious approach.

"Oh God, that's an understatement," she said when asked if court time was a goal this week.

Yet the ultra-competitive 27-year-old promised to heed medical advice.

"In the end it's up to me but I would never put myself out on to the court if it was detrimental to the team. If I'm not 100 per cent I don't want to do that to the team. They can continue on and I'll be the official timer," she said as a buoyant squad assembled at Melbourne Airport for the return home.

Williams was moving freely and felt no pain as she checked in but conceded her movements today were no comparison to four quarters against the world champions.

"I'm just walking, it's not what it's like to play so I'll have to wait and see."

Williams said she faced a mixture of rest and loading to see how the joint responded under stress. She was unsure how active she would be during training sessions in Auckland and would not put a time line on a final decision regarding her availability.

"We want to make sure we don't overdo it because it is a long time until the Commonwealth Games (Glasgow, 2014) that's ideally what I'm aiming for."

With that ambition in mind, Taumaunu will likely have to make do without her skipper from time to time to protect her longevity - just as All Blacks coach Steve Hansen accepts Daniel Carter will have to be carefully managed for the remainder of his test career.

"I've been doing that for about five years now," Williams said of her cycle of play, recovery and, if necesssary, rehabilitation.

"I wasn't given terribly good genes with my knees."

However, there are no issues with her eyesight and she was happy with what she saw from Silver Ferns goal circle defenders Katrina Grant and Leana de Bruin, who played out of position at GD.

"I think they did really well. In trainings and during the build-up to it I told them 'You've just got to tell each other what to do and how to do it and you respond to that'. They're quite honest and that's what we need."

- (Live Matches)