Paul Downing is ready to fight for his place in the Rovers side alongside Andy Butler, Tom Anderson and Joe Wright.
The centre-back, on loan from Blackburn Rovers, made an impressive debut in the Emirates FA Cup win over Oldham Athletic but is not taking a place in the starting XI for granted.
"There's really tough competition here. Generally you see football clubs have four central defenders fighting for two positions, and that can only benefit all of us as players and the team," he said.
"We have to play well to keep our place and stay on our toes if we want the jersey. Hopefully that will bring out the best in all of us and I'm sure we'll all be needed especially if the FA Cup run continues."
Downing expects Rovers to face another tough test on Saturday when they head to Portsmouth in Sky Bet League One.
"It's going to be a tough game down there, they've slipped a bit of late so I'm sure they'll be fired up to get back on track," he added.
"I played at Portsmouth on a Tuesday night last season and there was a good atmosphere so I'm expecting the same if not better on Saturday.
"I was happy to be thrown straight into such a big game against Oldham for my debut. There was a big crowd and an opportunity to put ourselves in the history books, so it was a good day all around but we need to forget about the FA Cup for a bit and focus on the league."
Rovers' next home game sees them take on Peterborough United on Saturday February 9. Ensure your place at that game by going to tickets.clubdoncaster.co.uk.