The Kangaroos have enjoyed the perfect semi-final tuneup with a comprehensive victory over Cook Islands in Townsville on Saturday night.

Australia ran in 12 tries to one to claim a 66-6 victory in front of 19,172 fans at Queensland Country Bank Stadium.

Back-rower Jacob Preston scored a try and showed why he's one of the best ball-running backrowers in the game, while Jack Bostock and Tom Trbojevic both scored hat-tricks and Tino Fa'asuamaleaui crossed for a double.

Ethan Strange was in the thick of the action in his Kangaroos debut and played lock after coming off the bench early in the second half.

Kotoni Staggs celebrates a try in Australia's big victory over Cook Islands. Picture: NRL Photos.

The triumph completes an undefeated group phase for the Kangaroos and was a significant improvement on last week's scratchy performance against Fiji.

Australia's focus will now turn to a sudden-death semi-final at Allianz Stadium next Sunday night.

The Kangaroos will likely play the loser of Sunday's blockbuster between Samoa and Tonga.

After two below-par performances to start their tournament Australia needed to find their rhythm in Townsville.

While they were not perfect against a spirited Cook Islands, the Kangaroos flexed their muscle to assert their status as World Cup favourites.

Bostock opened the scoring in just the third minute before the Aitu hit back and took the lead after Rua Ngatikaura burrowed over from dummy half.

Cook Islands threatened to score a second but the Australian defence held firm and the points started flowing soon after.

Four tries in 13 minutes saw the Kangaroos turn a 6-4 deficit into a 28-6 half-time lead.

Bostock crossed for his second soon after the break, triggering an avalanche of second half points.

Trbojevic scored his second, before Preston finished off a Cam Munster break and Fa'asuamaleaui produced a barnstorming solo try to bring up the half century.

The Kangaroos crossed for three more tries to close out the game while denying the Aitu's late bid for a try of their own.