The signing of Van Persie from Arsenal has sparked doubts on the progress of 21-year-old Welbeck, who forged a successful partnership with Wayne Rooney in attack for United last season.
However, Ferguson has alluded to the impact Eric Cantona had on 'Fergie's Fledglings' 20 years ago, claiming that Welbeck can learn a lot from the experienced 29-year-old Dutch striker.
"You can always learn from great players," he said. "Remember what Cantona did for all the young players when he arrived? He was a tremendous teacher for them.
"Danny will learn from playing with Robin, Rooney and Chicharito (Javier Hernandez). I think we have a great combination of strikers now and that's encouraged me.
"At 21 he's a young boy. He's still growing and has niggles, but he's going to be a big boy. He won't play every week but when he's 23 or 24 he'll be a fantastic player."
United will begin their Premier League campaign with an away game against Everton on Monday.