Either Bradford Bulls or York City Knights, who are both way out in front, will go up automatically and the other will fill the first play-off place.
That leaves Workington (28 points) and Oldham, Doncaster, Hunslet and Whitehaven (all on 26) challenging for the remaining three slots.
Oldham have the best for-and-against difference which could be worth another point.
The flip side is they have still to play joint leaders Bradford and York – Bradford at home, York away.
Their other four games are Whitehaven (home this Sunday); Newcastle Thunder (away), Coventry Bears (home) and London Skolars (away).
Doncaster and Hunslet are at home on Sunday against bottom-three sides so defeat for Oldham would probably push them down to seventh.
Said coach Scott Naylor: “It’s a must-win game, simple as that. We can’t afford to lose many more and this one is a four-pointer.
“In terms of retaining or improving our position it couldn’t be more important.
“Hopefully, it will be the start of a winning run which we haven’t enjoyed since we lost at Hunslet.”
Roughyeds are asking fans to turn up in numbers as strong home support on a compact little ground can be their 18th man.
They reported no new injuries after the win at Hemel and stressed that Danny Langtree’s withdrawal at half-time with a sore rib was merely precautionary.