"Give me the tee."

A Roberts penalty goal secured the Warriors their first premiership in nine years as they upset the heavily-favoured Kangaroos at Seiffert Oval on Sunday.

Trailing 18-6 at half-time, West Belconnen fought its way back into the contest to level it up at 24-all with seven minutes left.

It looked as though the Canberra Raiders Cup grand final would go to extra-time for a fourth consecutive year before a Brent Crisp shoulder charge sent West Belconnen half Cody Wynnik to the turf.

Roberts calmly slotted the penalty goal and somehow the Warriors had found a way to win.

Roos had a chance to put the game beyond doubt with nine minutes left before halfback Lachlan Cooper opted against a field goal attempt and took on the defence.

Cooper was pulled down on the last tackle, and just minutes later man of the match Tevita Aroha-Tuinauva scored his second try to bring the Warriors within two points.

Roberts' conversion from the touchline was followed by a bow to the hostile Roos crowd, and the rest was history.

Les McIntyre Medal winner Roberts struggled to find words to do the feeling justice after snapping the Roos' 16-match winning streak.

"They've had a great season and credit to them, but every side's beatable," Roberts said.

"On our day, we just proved we can beat anyone, and we went that way. We're on top of the world."

West Belconnen struck first as hooker Samuel Finnegan regathered his own grubber to score under the posts before Roos prop Jarred Pearce answered with a try of his own minutes later.

A converted Roos try extended the deficit to six and, until the half-time siren sounded, it stayed that way.

Roos centre Bryan Cronan flew over the dead-ball line to bat back a bouncing ball into the waiting arms of fullback Tre Williams to give their side a 12-point buffer.

Shades of the Canberra Raiders were on show at the club's first home ground when West Belconnen fans erupted into a Viking clap to welcome their side out for the second half.

It must have inspired something in the Warriors as Aroha-Tuinauva and Ryan McQueen both crossed the line before Troy Whiley pushed the Roos back in front.

West Belconnen coach Troy Thompson said game plans went out the window in the "surreal" dying minutes.

"Having a shoulder charge is probably a bad way to end for [the Roos] because they've been a great side all year," Thompson said. "But we've just got to take that. It's unbelievable."

Thompson said if anyone was going to stand up in the final moments, it was going to be Roberts.

"He just seems to have the knack for just doing something crazy and it's unbelievable," Thompson said.

Queanbeyan player-coach Aaron Gorrell was understandably disappointed with the finish, saying West Belconnen were the better side on the day "with some help".

CANBERRA RAIDERS CUP GRAND FINALS

First grade:

West Belconnen Warriors 26 (Tevita Aroha-Tuinauvai 2, Ryan McQueen, Samuel Finnegan tries; Robert Roberts 5 goals) bt Queanbeyan Kangaroos 24 (Tre Williams, Kody Parsons, Jarred Pearce, Troy Whiley tries; Brent Crisp 4 goals).

Reserve grade:

Queanbeyan Blues 34 (S Camaivuna, J Lenihan, T Jamieson, I Ngata, L Ahovisi, J Stuckey tries; S Taholo 3, F Skeen 2 goals) bt Tuggeranong Bushrangers 16 (A Wilkins, J Bramley, R Sheffield tries; M O'Malveney 2 goals). Player of the match: Phil Stonham (Queanbeyan Blues).

Under-18s:

Tuggeranong 16 (C Shingles, L Oakley, J Knight tries; J Heyman 2 goals) bt West Belconnen 12 (K Jensen, K Laundess tries; L Keeley 2 goals). Player of the match: Chris Shingles (Tuggeranong).

Ladies' league tag:

Belconnen United Sharks 20 (F Cooper, J Abel, S Carter, M Shevlin tries; M Shevlin 2 goals) bt Tuggeranong 4 (C Welch try). Player of the match: Renee Fleming.