The defending premiers slumped to their first loss of the season last weekend against Wellington and tomorrow they take on Group 11 leaders, Parkes Spacemen, in a blockbuster clash at Caltex Park.

Parkes are only ahead of the Fishies on for and against, making tomorrow a highly-anticipated top of the table clash, but Ryan feels his team haven't been at their best for some time now.

"I think the fact we've been winning has glossed over the fact we haven't been doing things 100 per cent so hopefully last week can make us turn that around," he said.

"We've conceded nearly 90 points the last three weeks so that's really alarming and certainly not what I enjoy."

For a team which prides itself on its defence, the Fishies in recent matches have leaked scores of 28 against Forbes, 24 against Macquarie and 36 last week against Wellington.

But Ryan said the attack has also not been at it's best and wants his team to be more focused this week against a Spacemen side which has scored more points than any other in 2015.

"Have a lot more patience, that's where we fell away last week and our attitude was off," he said.

"We've only seen them (Parkes) once this season and that was a draw but they've got a young side and they're quite similar to us.

"Dennis (Moran) is there orchestrating it all and they've got a big forward pack too."

Giving CYMS' chances a boost is the fact key Parkes players Tino Ionatana, Dave Masoe and Ben Nash will all be missing while winger Kevin Frank also looks set to miss out due to injury.

The Fishies haven't had the perfect buildup either with the forced closure of the fields in Dubbo during the week because of rain meaning Ryan and his men haven't had the chance to train.

Ryan doubted it would have any impact on his side but did admit powerful centre Jyie Chapman was likely to miss the match after coming off the field during the first half against Wellington last week with a lower back injury.

Despite there being four rounds remaining, this match will likely decide the destination of this season's minor premiership after the two sides drew their clash earlier this season 26-all.

But despite it shaping as a crucial match, Ryan wasn't reading too much into it.

"It wouldn't really matter too much (if CYMS lost), it wouldn't be the be-all and end-all but we are going out to win," he said.

The action at Caltex Park begins with the under-18s at 11.30am with the first grade clash scheduled to kick-off at 2.30pm.