Ronaldo scored 42 goals for United last season, but Rooney has already managed to score 32 for the Red Devils this season.
Ferguson told Sky Sports News: “I said a while ago it’s impossible for a player to get 42 but he is on 32 and there is a challenge there for him.
“He is capable of scoring in the next eight league games and five possible European games, so he has 13 possible games and you never know, I wouldn’t put it beyond him. I was just glad he got to the 30 mark, but we are enjoying his goalscoring.”
