Fifth-ranked Wangoom will face Killarney without two of its best on Saturday.
Opening batsman and handy bowler Chamika Fernando and opening bowler James Reid won't be available for the clash at Wangoom Recreation Reserve.
Fernando, who has hit four half-centuries this summer, injured his hamstring against Panmure in the Grassmere Cricket Association twenty20 grand final last weekend.
Captain-coach Lachie Morrison said his star opener, who scored 52 against the Bulldogs, was likely to miss two weeks.
The Roosters leader said number three batsman Chris Arthur would step up.
"He's usually pretty comfortable opening so he should be right stepping back up into that role," he said.
He added other opening batsman Jertho Serle was enjoying strong form.
Morrison said Reid was away on Saturday.
"We've got good depth in our B grade, there'll be a couple of blokes looking for a game," Morrison said.
The Roosters, sitting on two wins and three losses, are pushing for finals.
"I think we're in a fairly good position to get back into the (top) four," Morrison said.
The captain-coach said the Roosters had learnt plenty from their past couple of losses to Panmure in twenty20 and one-day cricket.
"It showed us that we need to step up our game," he said.
"We've really got to put some more value on our wickets and be really sharp in the field and bowl in the right areas."
Morrison is not taking the match against the eighth-placed Crabs lightly.
"This could be a crucial game, every game now is crucial," he said.
Killarney will be aiming to register its first win of the one-day competition.
Second-ranked Hawkesdale and top-of-the-table Panmure will play the match of the round at Hawkesdale Recreation Reserve on Saturday.
Mailors Flat and Yambuk will battle while Grassmere and Purnim meet.
Have you signed up to The Standard's daily newsletter and breaking news emails? You can register below and make sure you are up to date with everything that's happening in the south-west.