That's according to former United scout Mick Brown.
"He’s definitely one they’re interested in," he told Football Insider. "He fits the profile of a young player who they can help develop. They’ve had scouts watching him closely at Sunderland nearly every week this season.
"They will know how good he is and how far they think he can go in the game, and from what I’ve heard they’ve been very impressed. Man United have a very good relationship with Sunderland behind the scenes, too.
"There are a number of young players up and down the country that they’ve sent scouts to watch, but Rigg’s performances have been very, very impressive. I think they’ll keep an eye on his progress and then determine whether they think he’s ready for the step-up, but all signs suggest he will be capable."