On paper, top versus bottom represents a stroll in the park, but that is the furthest thought from the mind of the Saints' head coach ahead of Friday's home fixture.

"I don't think it will be a formality as some people may suggest," said Potter, who will be hoping to extend the leaders' unbeaten league run to six matches and maintain their four-point advantage over Leeds Rhinos. "We will have to apply ourselves or we could be in a worrying position."

Saints didn't exactly have matters their own way when the clubs met at the Brewery Field on a wet and drizzly Saturday night in early March, edging to a 4-0 victory.

"The conditions were not ideal for playing open rugby - the pitch was heavy and the ball slippery - but I think it will be a different kettle of fish on Friday," said Potter.

He added: "The Crusaders play a similar band of football to Castleford, they enjoy a lot of set plays, and have good width when they get down to your end of the pitch and they can certainly frustrate you as they did against Wigan a few weeks ago."

Saints are expecting to have scrum Sean Long back after missing Sunday's game at Bradford due to calf and achilles problems, and despite having 18 stitches in a head wound following an accidental collision with Bradford's Paul Deacon, Aussie centre Matt Gidley will also be available for selection.

So, too, will Chris Dean who suffered a minor neck muscle injury in the same match and Jon Wilkin - withdrawn on the hour mark suffering from cramp in both calves.

However, there are question marks over the fitness of up-and-coming youngsters Jonny Lomax and Gary Wheeler.

Lomax took a blow in the back when playing for the reserves in the Odsal curtain-raiser and Wheeler pulled up during an extra training stint with a calf strain.