Sonny Bill Williams won't find a better stage to show he's All Black material than he gets in Sydney next week, says former All Blacks halfback Justin Marshall.
Marshall believes Williams' appearance in a star-studded Barbarians team against the Wallabies in Sydney on Saturday week will give a good indication whether he has the potential to become a dual international.
Playing in France, Marshall has been been able to monitor the progress of the former New Zealand rugby league Test palyer since he controversially switched codes last year to join French club Toulon.
He already rates Williams a successful convert but says the 23-year-old gets a platform to show how far he could go when he plays in a world-class Barbarians outfit boasting some 850 Test caps.
Marshall says Williams' transition has been the more impressive given it has required a move from the back row, where he played most of his league, to the centres in rugby.
Marshall, who's part of the Barbarians line-up says he's pleased to be playing alongside Sonny Bill rather than against him.