And with Doncaster standing in the way of three crucial promotion points at the Keepmoat this weekend, McLeish would be happy to see the 22-year-old struggle against his forward line.
"Mills was a young player that I thought could get even better," said McLeish on the club's official website. "I hope he has an off day on Saturday.
"He certainly impressed us this season. I've watched him a number of times, but the whole Doncaster team have impressed us. We've got to go and stamp our whole identity on the game and try and pull off another great away victory.
"I expect he (Mills) will be motivated to play well because there will be a lot of scrutiny on him. I hope I've not put his confidence up ten-fold but at the same time I would expect him to give a professional performance."