Oldham are just 80 minutes away from gaining promotion to the Championship.
Oldham beat Doncaster 22-12 in their League 1 play-off semi-final at the Vestacare Stadium.
Dave Hewitt, Emmerson Whittel and Paul Crook scored for the Roughyeds.
Doncaster get another chance to reach the play-off final though as they take on Newcastle Thunder in the preliminary final.
Thunder beat Workington Town 38-18 at Kingston Park on Sunday.
Kieran Gill (3), Nick Newman (2), Quentin Laulu-Togaga’e and Alex Clegg crossed the whitewash for Newcastle.
Workington only had 14 fit players due to injury, with Fuifui Moimoi played the full 80 minutes four days before his 40th birthday.
Oldham will have a week off now, while Newcastle-Doncaster play next Sunday in the North East at 12pm.