Defending premiers Thirroul showed they won't easily surrender their title in 2015 with a commanding 26-4 Challenge Cup victory over Collegians on Saturday.

Playing at home, the Butchers ran in four second half tries to overcome a game Collegians outfit who also confirmed their premiership credentials, with the scoreline not reflecting their efforts.

Butchers five-eighth Ty McCarthy scored two tries and linked well with new halves partner Willie Stowers while former Origin and Test forward Trent Waterhouse produced a dominant display up front.

Butchers captain-coach Luke Swain, who also impressed after two years out of the game, was happy with the performance.

"They came out of the blocks firing and were really physical to start the game," Swain said.

"We've had a really big turnover of players from last year and a few new combinations but the boys really turned up today and it was a really good performance."

The see-sawing battle was locked at 0-0 after the first quarter and 4-4 at half-time, with Lee Higgins scoring the Butchers' first and Collies recruit Sam Racicava hitting back after some good lead-up work from former Rabbitoh Brett Kearney.

Mitch Bate and former Panthers first-grader Geoff Daniela crossed after the break before McCarthy's late double sealed the win.

Collies coach Reece Simmonds was pleased with his side's performance despite the scoreline.

"We only fell away right at the end there so I'm not all that worried about it," Simmonds said.

"I'm more focused on the start of the competition. We've only got six players from last year in the team that played today so we're a new squad and we just need game time together and we'll improve from here."

The Butchers' victory came in the second leg of a double-header, with Wests scoring eight tries to beat Dapto 46-8.

Mitch Porter scored four tries while new recruit Daniel Holdsworth showed that he and halves partner Nathan Dureau have the potential to be the best six and seven combination in the competition this year.