The 22-year-old has become an integral part of Jose Mourinho's squad at the Santiago Bernabeu since joining the La Liga giants from Werder Bremen in 2010, and speaking to Welt, Mustafa believes his son can do more at Real, and could even surpass Lionel Messi.
"I don't think that Mesut has already reached his peak. He still has plenty of potential," the proud father crowed.
"Just look at how Barcelona play. Ten players are all running their socks off for Lionel Messi.
"Mesut is the No. 10 as well at Madrid, but the other players are not working for him. Mesut still runs between 12 and 14 kilometres per game.
"He collects the ball at the back and then directs play from midfield. That burns a lot of energy. I am confident that he will become the star player at Madrid if he continues to develop like this", Mustafa concluded.
The Germany international has made over 60 appearances for the La Liga side.