INJURED Kangaroos utility Jess Sinclair has challenged Lachlan Hansen to take his place in the side, now vacant for at least the opening month of the season.

Hansen, the No. 3 pick in the 2006 national draft, is seen as a long-term prospect in defence for the Roos after coming to the club from Nar Nar Goon in country Victoria.

Sinclair said Hansen would battle fellow youngster Gavin Urquhart for the vacant spot in the side.

"I reckon Gavin Urquhart, a young kid from Queensland, he's played NAB Cup and the last two practice matches, he's been very impressive," Sinclair said.

"Also I think Lachlan Hansen … he's also played every game and he looks very positive as well.

"One of those will most likely step up and hopefully they can play a role."

Sinclair needed surgery to re-attach ligaments in his injured thumb and will be out for up to six weeks.

He fell on top of the thumb last Saturday after losing his balance in their 36-point practice match win over Fremantle at Subiaco, but continued playing after the injury.

"I panicked a bit when I first looked at it, I didn't know what to do, I ended up handballing the ball which wasn't smart," Sinclair said.

He is frustrated with the enforced lay-off after completing a full pre-season, but aims to return for the Kangaroos' round-four clash against Melbourne.

Sinclair will probably wear a protective guard when he returns.

AAP