The Royals striker has scored seven times since the turn of the year and is earning a reputation as something of a super sub.
A boyhood United fan, the 26-year-old actually had a trial for the club at the age of seven before working his way up the footballing ladder from nearby Stockport County.
"I watched Le Fondre when he was at Stockport," revealed Sir Alex. "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. It's been a turnaround for Brian McDermott since Christmas. It looked as if they were destined to go down but now they're rescuing games in the last few minutes.
"They beat Sunderland and West Brom at home and snatched a point against Chelsea after being 2-0 down with a few minutes left. So there's a bit of fight in them, you know."
Le Fondre, who scored in his side's 4-3 defeat at the Madejski Stadium earlier this term, will be keen for a start as McDermott may shuffle his pack on Monday.