Petrucci made his Posh debut on the weekend.
"Actually, I've been playing with him around 11 years! I've known him since I was 10 years old so we know each other very well! I lived five minutes away from his home in Rome. We are very good friends. I hope now he's gone to Peterborough that he starts to show he is a top player. He has had many injuries and I think he deserves that chance," Macheda told manutd.com.
"He was out for around two years but now he's been back playing for a year and a half now so it's a good thing for him. I think he's going to do well once he gets the opportunity."