The Illawarra Coal League grand final will be a northern derby after Helensburgh overturned a 10-point half-time deficit to overcome Wests 22-16 in Sunday's preliminary final at WIN Stadium.

Just a week after going down 19-18 to Thirroul in the major semi-final, the large number of Tigers fans who made the trip south were forced to endure more nervous moments with the match locked at 16-all for the majority of the second half before a late try to Jason Raper sealed the win.

It sets up a mouth-watering grand final clash with fierce northern rivals Thirroul on Sunday.

Tigers coach Ryan Powell praised his side for pushing past the mental scars of their tight loss to the Butchers to earn a shot at redemption this week.

"That was just guts, it was a gutsy win," Powell said.

"What they went through last week [against Thirroul] was mentally pretty tough and that sticks with them. It's still with them now and it's still hurting.

"Those guys who were physically belted around ... it's hard to take but they got their heads together to get up and do their job still.

"Mentally right across the board we didn't have a single bloke who didn't do his job today so you can't be happier than that."

The Burgh shot out of the blocks when five-eighth Jarrod Boyle found an unmarked Azan Turoa with a pinpoint long ball after just six minutes with Eamon Hillen's tough sideline conversion giving them a 6-0 lead.

The injection of Wests skipper Jason Ryles and veteran prop Greg Reh in the 16th minute swung the momentum sharply back to the Devils with Ryles carrying for defenders across the try line to level it at 6-all three minutes later.

Wests took the lead in the 29th minute when Turoa fumbled a Clint Wright kick close to his own line with Bart Hill on hand to collect the scraps and score.

The usually sharp Mitch Porter missed the conversion keeping the Devils' lead to just four at 10-6.

It looked ominous for the Tigers when Wade Standford strolled over from dummy half six minutes before the break to extend the lead to 16-6 at half-time.

The Tigers fought their way back into the match on the back Boyle's boot early in the second half with deft kicks and determined chasers forcing three goal line dropouts in opening 10 minutes.

Hooker Dan Fepuleai forced his way over from dummy half following the first restart to cut the lead to 16-12 with 30 minutes to play before Wayne Bremner produced perhaps the try of the season six minutes later.

With golden point looming for the second time in a week, the Tigers looked to Raper to swoop on a Rhian Gerard offload to cross and seal the match three minutes from time.