Wests found the answers when they needed them to prevail in a scrappy elimination final against Collegians at Dapto Showground on Saturday.
The Devils won 32-18 after leading 20-6 at half-time.
The Dogs fought hard to stay in the contest, but never looked like snatching victory to keep their premiership defence alive.
Wests assistant coach Mark Riddell admitted after the match that a big improvement was needed if the Devils want to be any chance of beating Helensburgh in the preliminary final this Sunday.
"We were really happy with our first half. We thought we were working really well but the second half, with the standards we've set over the past month, was really poor," Riddell said.
"At half-time we spoke about going on with it but I thought we came out really lethargic and I thought there was a real lack of energy, not in just one or two players but across the whole side.
"We turned over way too much ball in the second half and invited Collies back into the game.
"You can't afford to do that in the big games."
Wests were on the board after just two minutes when Zac Hill dived on a deflected Clint Wright kick to post the first try, which Mitch Porter converted.
The Dogs hit back midway through the half when prop Kane Skarrats charged down a Brad Scott kick and regathered to run 50 metres and score.
The deadlock was shortlived as a Collies mistake on the kick-off reception allowed Aaron Heartsch to retake the lead at 12-6. Heartsch's second try eight minutes later extended the lead before a penalty goal to Porter gave the Devils a 20-6 buffer.
Collies started strongly in the second half and got back in the game through a Brayden Dwyer try after 10 minutes but Wests were safe when Greg Reh put Scott across for a 26-12 lead with 15 minutes left.
Jay Bonnell scored another try for Collies before Clint Wright crossed for the Devils on full-time.
Collies coach Reece Simmonds praised his side's courage after the match.
"We tried our hardest and never gave up and we fought it out to the end. I commend our guys' effort today, it was great."