Le Fondre won last month's Premier League Player of the Month award and will start in tomorrow night's FA Cup tie.
Ferguson admitted: "It's certainly unusual for a substitute to win the award, that's for sure.
"A lot of teams have players who can come on and be goalscorers, the likes of Ole Gunnar Solskjaer for us. He was a terrific substitute, Javier Hernandez is the same.
"Reading have scored late goals. Brian McDermott has had a turnaround in results since Christmas. It looked until then that they were destined to go down.
"Now his team are rescuing games in the last few minutes. That's given them positive results, including against Sunderland. They also beat Everton at home and snatched a point against Chelsea after being 2-0 down with just a few minutes left.
"There is a bit of fight in them and it's always a good atmosphere at Reading. They have a big, important game on Saturday at home against Wigan so I'm wondering what kind of team they will play against us. I'd be surprised if Brian plays his strongest team, but you never know."