With the Raiders and South Sydney Rabbitohs playing in both the NRL preliminary final and the Jersey Flegg under-20s grand final this weekend, Don Furner felt it was the perfect opportunity to turn it into a Canberra Stadium doubleheader on Friday night.

Instead the Raiders and Rabbitohs will fight for a spot in the NRL grand final at Canberra Stadium on Friday, while the under-20s decider will be played at Parramatta Stadium next Sunday.

Given the NRL game's expected to have the Raiders' biggest ever ACT crowd, Furner felt the Jersey Flegg final could've been turned into a spectacle.

Instead it will be played as a curtain raiser for the NSW Cup final a couple of days later.

"Very disappointed NSWRL couldn't make the change, was very limiting and short-sighted," Furner told The Canberra Times.

"The chances of having both Raiders and Souths play together was a great opportunity to play in front of a sellout crowd.

"Instead it will be played with no one in the crowd in Sydney."

But Raiders under-20s coach Ash Barnes said it would be a massive week for the club with both teams still in the hunt.

They reached the grand final with a 22-12 victory over the Sydney Roosters at Kogarah on Saturday night.

Tries to Kai O'Donnell, Joe Roberts, Manase Kaho and Lachlan Lewis set up the win and a spot in the decider.

"It's going to be a massive week for the Raiders' NRL squad, but now obviously for the club as a whole," Barnes said.

"It's very exciting at the headquarters at the moment, a really good atmosphere, and it's going to be a big one.

"Going up against Souths in the two grades it will be a great weekend to look forward to."

NRL PRELIMINARY FINAL

September 27: Canberra Raiders v South Sydney at Canberra Stadium, 7.50pm. Tickets on sale Monday (members) and Tuesday (general public).