Giant winger Ratu Nasiganiyavi has starred in the Australian Under-20 rugby side's 81-12 victory over Canada in their opening match of the junior world championship in Wales.

The game was effectively over as a contest in the opening 20 minutes with the Australians running in four converted tries through captain David Pocock, Ben McCalman, Rob Horne and James Hanson.

Western Force fullback Dane Haylett-Petty scored four tries in the 13 tries to two rout while Nasiganiyavi claimed man of the match honours for his menacing performance - which included two five-pointers.

Nasiganiyavi, the cousin of Lote Tuqiri, signed a two-year deal with the NSW Waratahs for the next two Super 14 seasons following his barnstorming performances for Sydney grade side Randwick this season.

Australian coach Brian Melrose was happy with the performance.

"It was a good start and good to come away without any bad injuries as we had a bad week losing a couple of backs," he said.

"It's good to get off the mark and we've got a line in the sand now but we do need to make improvements in some areas."

Australia 81 (Dane Haylett-Petty 4, Ratu Nasiganiyavi 2, Junior Sovala 2, Ben McCalman 2, Rob Horne, David Pocock, James Hanson; Quade Cooper 5 cons; Jeremy Sua 3 cons) defeated Canada 12 (Matt Evans, Sean White tries; Nathan Hirayama con) at Rodney Parade, Newport, Wales.

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