Dumped Wallabies backrower David Lyons is the front-runner to replace injured No.8 Toutai Kefu in Saturday's Bledisloe Cup showdown with the All Blacks if Australia's key ball-runner is ruled out.

Kefu must run at pace on his strained calf or risk being left behind on Thursday when the Wallabies fly out to Auckland for their crucial trans-Tasman clash.

A loss at Eden Park means the Australians will hand over to New Zealand the Bledisloe trophy they have held since 1998.

The Wallabies have other injury concerns with their two tighthead props Patricio Noriega (groin) and Glenn Panoho (corked leg) both failing to train.

NSW rookie Alastair Baxter, who hadn't trained with the squad at Coffs Harbour before let alone played a Test, arrived and was put on standby should either of the veteran props fail to recover.

Kefu has recovered from his bruised spine, suffered in a late tackle during Australia's last Tri-Nations Test win over South Africa, and was frustrated to be battling a new injury.

"Kef trained lightly today, we're reasonably optimistic he's going to be right to play but he'll have to train tomorrow," Wallabies coach Eddie Jones said today.

"He's going to have to show tomorrow that he can run at a reasonable pace."

Jones considered switching blindside flanker George Smith to No.8 if Kefu was ruled out when the side was named tomorrow, but Lyons was more likely to be chosen.

Axed after Australia's opening loss to South Africa in Cape Town, Lyons impressed Jones enough at training to edge ahead of Owen Finegan, who has been on the reserves bench since returning from a shoulder reconstruction.

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