• The Kangaroos top Pool A with 66-6 victory in Townsville

• Tom Trbojevic scores second hat-trick in as many games

Reece Walsh showed if there was anything James Tedesco could do, he can do better with a starring role for the Kangaroos in a partly clunky but otherwise entertaining victory over the Cook Islands in Townsville.

Coach Kevin Walters faces a choice between the two brilliant No 1s for the much-anticipated semi-final against either Samoa or Tonga next week, but this only sometimes convincing display showed there is still work to do in camp Kangaroo.

It was not quite a horror show on Halloween, given the way the Kangaroos improved after the break. But 15 errors will only amplify concerns the Kangaroos – despite their three victories in the tournament and Saturday’s hat-tricks to wingers Tom Trbojevic and Jack Bostock – are still shy of their best.

Walsh was the standout with one try, five try assists as well as a hand in another. He shrugged off ankle and shoulder complaints in the second half to spearhead a series of free-flowing attacking forays. The combinations in what appears to be Australia’s first-choice spine of Harry Grant, Tom Dearden, Cam Munster and Grant improved as the match wore on, and were capped off by a late try for Grant off an inside ball from Walsh.

A six-try blitz in the first 20 minutes after half-time had earlier ended the contest, though the valiant Cook Islanders were unlucky not to add a second in the final minutes. Two hours beforehand, the match could hardly have started worse for the underdogs. The Kangaroos’ first kick was fumbled under pressure by winger Cameron Brown, and Australia scored in the ensuing set. It was thanks to an incisive contribution for Walsh, who drew in the right winger Esan Masters then lofted a pass to put Jack Bostock over in the corner untouched.

But Australia’s inconsistency has been a feature of this tournament, and it was obvious again after 10 minutes. Grant got caught up with Masters when he was chasing a kick, and the Cook Islands had a set 10m from the Australian line. A dummy from hooker Rua Ngatikaura was enough to fool markers Pat Carrigan and Liam Martin, and a converted try put the Cook Islands ahead.

The mistake was compounded when Walsh kicked out on the full from the kick-off, and then Tom Dearden gave up another set with a ruck penalty, but an inexplicable second tackle kick let the hosts off the hook. Another error due to a wayward pass from Grant, and suddenly the Cook Islanders were back on the Australian line, but another poor kicking option let them down.

Former Kangaroo Val Holmes was at fullback for the Cook Islands, representing the country of his mother’s birth. Prop Davvy Moale and captain and centre KL Iro were other NRL-calibre players in the side, as well as 20-year-old Warriors’ five-eighth Maui Winitana-Patelesio. The depth was lacking, however, and the side relied on former Eel, 37-year-old Brad Takairangi, at halfback fresh off a season with the Glebe Dirty Reds. To his credit, he looked a player 10 years his junior, with one tackle on Trbojevic flattening the Australian winger.

The gulf in class was obvious when the Kangaroos regained the lead with a simple blindside raid down the right, as Trbojevic finished interplay from Grant and Dearden. A Holmes error handed the ball back almost immediately, and the Kangaroos had their third try when Tino Fa’asuamaleaui crashed over.

Cam Murray had been named on the bench, but was ill at Friday’s captain run and was replaced by David Fifita. Murray suffered a head knock last week against Fiji, but returned to finish the match and was one of Australia’s better forwards. There had been criticism levelled at the pack over the past two weeks, but Fa’asuamaleaui, Pat Carrigan and lock Isaah Yeo looked predictably comfortable against lesser opposition.

Backrower Jacob Preston, whose CV is perhaps the shortest of any among the starters, appeared eager to show Walters that he – rather than Fifita – was worthy of the Kangaroos No 11 jersey with strong running. His first line break led directly to another try, when Dearden found Kotoni Staggs out wide. Preston repeated the fear with seven minutes to go, putting Walsh over this time for Australia’s sixth try. He would get his own midway through the second half.

Next week’s semi-final loomed large when Trbojevic and Munster suffered minor ankle injuries, even if both shook them off. But injuries could not be blamed for an ongoing clunkiness in the Kangaroos’ play. The first half ended 28-6, but the Cook Island almost had a second in a late siege resisted by stout Australian defence.

Canberra five-eighth Ethan Strange came on for his first appearance in green and gold in the second half. From his first play the ball Bostock went in for his second try. Again it was Walsh who made the critical contribution, batting the ball on to avoid the jamming defence. For Trbojevic’s second minutes later, it was Walsh again with the final pass. Those two combined again for Trbojevic’s second hat-trick in two weeks, and then Bostock bagged his own triple. But their try-scoring feats will be forgotten when the tournament really begins at Allianz Stadium next Sunday.