McDermott's side have already faced three of their four Yorkshire rivals in the Sky Bet Championship this season, drawing 1-1 with Sheffield Wednesday at Elland Road and losing 3-2 at Huddersfield, while beating Doncaster 3-1 in the Capital One Cup at the Keepmoat Stadium in August.
Doncaster have won only two of their last nine league games, but one of those was against QPR.
"They scored a late goal against QPR and we've already played them once in a cup game," said McDermott. "It was a good game.
"It's like every Championship game you're involved in, you know, especially with it being a derby, with Leeds coming to town, it's a big game, a big event.
"We'll be ready and we're looking forward to it."
Leeds defender Scott Wootton scored on his debut at Doncaster in August and teenage midfielder Alex Mowatt made his first start f or McDermott's side against his hometown club.
Leeds have won four of their last six league games to keep in touch with the top six and after fighting back from two goals down to draw 3-3 with Watford last week, McDermott said his players were in good heart.
"We know we're going to be up against a side that work really hard and it's a derby," McDermott added.
"There's going to be a good atmosphere in the ground and we know what we're going to come up against and we'll be ready."