In this week's edition of MUTV's Thursday Focus, the Red Devils skipper spoke glowingly of the 18-year-old striker who continued his rise to the top with a goal in the 3-1 EFL Cup win at Northampton Town on Tuesday.
Rooney feels Rashford has all the attributes to be a superstar for both United and England for a very long time to come.
"Marcus is incredible," said Rooney.
"He was thrown in last season when we, the other players, weren't sure he was ready. But he was thrown into the [Midtjylland] game and got two goals. Since then, he hasn't looked back.
"I think his attitude is fantastic. He wants to work, he wants to learn and some of the younger players nowadays in football haven't really got that attitude. It's great to see and he's getting his rewards for it. He is some talent and, if he keeps going, he'll be a real star for this club and for England.
"Of course, we encourage him but, with players like that, you just want to let them play. You don't want to teach them how to play football because they [already] can."