United host the Royals in a fifth-round tie tonight, with Le Fondre on a fine run of form that saw him collect the Barclays Player of the Month award for January.
Le Fondre scored five times in the Premier League last month from the substitutes' bench and Ferguson has admitted that the forward's impact in the top flight has been a pleasant surprise.
He told The Sun: "I watched Le Fondre when he was at Stockport. It's a big jump to come from Stockport to the Premier League. You've got to give the boy credit.
"He came on at Stoke last weekend for the last 10 minutes and almost got a penalty kick and had a shot blocked. A lot of teams have got players who tend to be a good substitute like Ole Gunnar Solskjaer was, for instance, and Chicharito is another one.
"I think Le Fondre has done most of his scoring in the home games and he's scored late goals for them."
The 26-year-old has 12 goals in all competitions for Brian McDermott's team this season.