Zavon Hines, who has three goals to his name this season, is struggling with a knock and Allen now believes he should have remained on the bench in midweek.
“Zavon Hines has a sore knee,” he told the Derbyshire Times.
“I made a big mistake in playing him on Tuesday night.
“He should have been rested, been a sub and gone on for 20 minutes when we needed a goal.
“I played him because he’s been our most talented forward, with the ball at his feet he’s a real danger.
“So I made that decision late on Tuesday to play him on the right and it didn’t work.”
The manager and his staff will assess Hines today and tomorrow before deciding on the role Hines will play in the game at home to Dover.
“We need to make sure his knee is right before Saturday’s game and I need to decide whether he’s a sub to come on or fit him up front,” said Allen.
“I need everyone for this game on Saturday, 110 per cent.”
Charlie Carter (ankle) remains a week away from a return to action while Sam Wedgbury goes in for his knee operation today.
“Everyone else is physically fit and everyone has got to be 100 per cent fit mentally,” Allen added.