The Devils accounted for De La Salle 30-16 at Parrish Park, but the 2pm kickoff saw the drama continue well after fulltime as Collies mounted a rear-guard action against Helensburgh kicking off an hour later.

The Dogs needed to overcome a 62-point differential gap to leapfrog the Devils and fell agonisingly short, running in 12 tries in a 70-12 win that was a dramatic race against the clock.

Falling four points short will see Nathan Fien's side remain in third spot and take on De La in the minor semi-final next weekend.

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It leaves Wests one game away from a grand final appearance and taking strong form into the major semi after kicking clear of De La with three second-half tries for a 30-10 margin.

It followed a hard-fought first half that saw De La lead 10-8 before Devils five-eighth Hamish McLaurin crossed on the stroke of halftime for a 14-10 lead.

Grinding it out from there was the perfect finals rehearsal for Pete McLeod's side heading into the clash with Thirroul, who comfortably saw off Corrimal 34-16 at Gibson Park.

"It was a better performance than what we've dished up in big games previously and it was just a more consistent effort over 80 minutes," McLeod said.

"We spoke all week about that 80-minute effort and that at this time of year, August-September, the level of footy goes up.

"We're playing good teams and you need to have a consistent effort. You can't afford to have 10 or 20 minutes where you go away from it.

"There's good teams in this comp with good players that turn up every week. The way it's been over the last couple of years, we've just really focused on ourselves.

"You just need to play to the best of your ability and I know I've got the calibre in the room to be a chance in any game."

With COVID scuppering the last two Illawarra League seasons, Saturday's main game will be the Devils first finals outing since dropping the 2019 grand final to Collies.

"Its my fifth year coaching first grade and the first couple of years we played grand finals and since then we've been away from it," McLeod said.

"In 2020 we played in Sydney and last year it got called in the middle of the year so the boys are really hoping we can play some good footy over the next couple of weeks and get some rewards.

"It's been a tough year for everyone with the weather and trying to get on the field but hopefully we get some sunshine and we can train on football fields and we can put some good performances in."

De La didn't leave Parrish Park too disheartened, though coach Luke Manahan will have some headaches with prop Sione Afemui placed on report three times in the loss.

Having fought back to the lead in the first half, conceding a try moments before the break and then squandering one when fullback Logan Aldridge spilled a pass with only clear air in front of him proved costly for the league newcomers.

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It came midway through the second half with the score locked at 14-10, the Devils responding with three tries that put the game beyond reach.

Manahan said letting teams off the hook is a trend his side will need to address to be any chance of making a finals run count.

"It was the same as a few other games this year against Thirroul, the first time we played Wests as well, we had our hands around the throat but we just struggled to capitalise on that," he said.

"We were right there with them and we made that break and we probably should have scored points but we didn't and then it completely swung around.

"A couple of our errors or penalties compound and it turns into a 12-18-point swing and it's just very hard to come back against these teams.

"There's just little moments in our games that we've got to fix. If we fix those things we know we can beat any team in this comp."

It will have to be Collegians first up in the minor semi-final, the only top four side they've managed a win against this season.

It adds to the belief, but Manahan said the opposition was immaterial given how little's between the finals combatants.

"We haven't thought about [who we'd play] too much, we just wanted to get to finals and anything can happen from there," Manahan said.

"It doesn't matter who it is, we know we'll turn up and have a quality opponent. Whoever it is we know we can match it with them.

"Our goal at the start of the year was to win more games than we lose and hopefully secure a finals spot.

"We've done that now but, as the season's progressed, we've realised we can match it with the top teams. We're not here to just come fourth and settle for next year.

"We're ready to go into next week in that do-or-die game and hopefully progress through and give ourselves a chance to get to the [grand] final in a few weeks' time."

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