It was one of 10 tries in a high-scoring affair but both coaches agree Thirroul forward Joel Ruskin's 39th-minute four-pointer was the most telling moment of the Butchers' 34-24 minor semi-final victory over Dapto on Saturday.

The Canaries played their best football of the season to lead 12-0 on the back of tries to Troy Pieper and Daniel Moroko before Ruskin's barge-over solo effort from 10 metres out cut the deficit to just six at the break.

Ty McCarthy crossed just minutes after the resumption with the first of five second-half tries to overwhelm the Canaries and book a preliminary final showdown with Helensburgh this Saturday.

"In big games you need big plays and that turned the game massively for us," Butchers captain-coach Luke Swain said. "That really hurt them psychologically I think. You could see their heads went down a bit.

"It was a big play in a big game, so that was fantastic."

It was a half-time margin that flattered the Butchers, who spent the bulk of the first half camped at their own end after a flying start from the home side who completed all but two of their sets in the first half and forced five line drop-outs off the boot of Pieper and five-eighth Freddie Robinson.

They went close to extending the lead on several occasions but were denied by some desperate Butchers defence, with Swain praising his side for not conceding more points in the onslaught.

"I thought we were good in the first half," Swain said.

"We gave away a few too many penalties but we still completed at around 90 per cent. It was the best we've defended all year, especially on our line, and we needed to because they had all the ball.

"They broke us a couple of times but we knew we could hold on if we could just get the flow of possession back. We know if we hold the ball and don't shoot ourselves in the foot, we can beat other teams with the experience and talent we've got."

Ruskin's try was part of a big contribution from the Butchers' bench with young gun Max Bailey making the most of his call-up from the under 19s to score back-to-back tries midway through the half to put the game out of Dapto's reach.

Leigh Higgins and Joel Johnson also got across for Thirroul, before Andrew Madden and Jess Morris picked up late consolation tries for Dapto.

Departing Canaries coach Chris Leikvoll also pointed to Ruskin's try as the turning point. "We were very good in the first half but had that one mishap at the end there and never really recovered from it," he said. "Unfortunately Thirroul played for 80 minutes and we probably only really played half a game."