Skipper Dan Boatman with last week's ball boys
Chapman finished the game against Sheffield last week after the lively Joe Rafferty had to leave the field with a shoulder injury.
And another replacement also keeps his place - Darren Thomas will be at scrum half for the unavailable Ryan Painter, while Scott Butcher returns on the wing.
Andrew Foreman will be on the bench to provide backs cover alongside Carl Robinson and Gary Jackson.
The club is also turning out Stags, Bucks and Colts teams this week despite a litany of injuries to regular first teamers. Unavailable to the coaches this week are Andy Robson [recovering after a car crash in May], Owen Bennett [training again after an eye op in the summer], Andy Dixon [recovering from an eye op], Joe Rafferty [shoulder], Liam Bailey [shoulder], Ian Pinchen [making progress on a shoulder injury],Ryan Painter [holiday] and Jack Angus [suspended].
When that lot return there will be some competition for places - specially in the forwards. However, the incumbents have not been doing themselves any harm with the very young pack putting on a superb show in the first half against Sheffield.
They'll have to work just as hard against an experienced South Yorkshire side who know how to use their sloping pitch to their advantage.
This is the highest level they've ever played - overcoming Bradford and Bingley in their first game on their own pitch last week. They raced into a 22-0 lead in the first half with the slope but conceded 13 in the second.
West: Stu Waites, Scott Butcher, Andrew Cheslin, Peter Youll, Luke Mallinson, Zac Southern, Darren Thomas, Michael Hogan, Andrew Rollins, Adam Coates, Luke Chapman, Chris Atkins, Alex Barker, Dan Boatman [captain], Sam Miller.
Reps: Carl Robinson, Gary Jackson, Andrew Foreman.