Last year's grand finalists are in a do-or-die clash with Wellington Redbacks at Bowen Oval on Sunday afternoon with the winner advancing to the preliminary final and the loser booking their end of season trip.

Wellington president David Grant says the Redbacks have trialled well during the week and while aware Coolah will be a major task at home there is a confidence among the players.

"Our coach Chris George believes Wellington is in with a really good chance. The side toughed it out against the Rhinos last week and Coolah was well beaten by Yeoval and will be sorry and sore but will be difficult to beat at home," he said

For Coolah it's not just facing elimination the daunting prospect for coach Andrew McFadyen, it's the number of players he doesn't have at his disposal because of injury.

"We are in a bit of trouble," McFadyen said.

"Injuries are my biggest concern. I hope to have fit 15 players. I hope I can put a competitive side on the park."

The early signs weren't looking good for McFadyen who only had nine players at training on Tuesday night.

Injuries have been a key reason the Roos find themselves in the "must win" position.

"It has been a big challenge for us this year," he said.

"We have achieved every bit as we did last year because we've basically had to rebuild the club after last year's [grand final] effort."

McFadyen said Yeoval were a class above his team and were rightful winners in the qualifying semi-final last week.

"Despite the 42-7 score we defended really well. But when we had the ball we were ordinary," he said.

Playing against Wellington, McFadyen knows it will be a tough assignment.

"They have a good forward pack, lot of experience there too. There is nothing between the sides," he said.

"We got the points in the last couple of minutes when we played them here last time.

"I hate to say it but I think we are the underdogs because we simply don't have the cattle.

"If we have a fit squad, there is no reason why we can't play next weekend [in the preliminary final].

"We're not writing ourselves off yet. Sometimes the rugby Gods are smiling on you and sometimes they're not.

"I believe we can win but only if we put in a good performance.

"If we make errors and not play like we are supposed to play, then it will be curtains for us."

Yeoval will travel to Dubbo to meet Rhinos Gold on Saturday in the major semi-final at 3.15pm.