All Blacks halfback Jimmy Cowan is in serious doubt for the second Bledisloe Cup rugby test in Christchurch next Saturday after suffering rib cartilage damage during Saturday night's 49-28 victory over the Wallabies at Etihad Stadium.

Cowan was replaced by Piri Weepu in the 33rd minute of the first half and All Blacks head coach Graham Henry said he was unlikely to feature when New Zealand attempt to retain the Bledisloe Cup and close in on recovering the Tri-Nations trophy with a fourth successive victory at AMI Stadium.

"He tells me he's going to be fine but I think he'll struggle to be right for next week," Henry said.

Cowan owed his start against Australia to Weepu's delayed arrival in Melbourne after he became a father for the first time last weekend.

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