The summer signing from Cerro Porteno has been gradually building up his match fitness in U21 action this season.
Wing-back Leon has made the matchday squads against Grimsby Town, Manchester City, Brentford and Sunderland this season, without taking the pitch.
However, the Manchester Evening News says United management have plans in place to get Leon to the stage where he will be ready to taste Premier League action.
United U21 coach Travis Binnion said, "It is evident for all to see he has some real qualities and some strong foundations to his game that he has to build on.
"He is aware, we are all aware, he has stuff to work on but to be fair to the kid, he has not played a full 90 minutes yet. We will be looking to tick that off pretty soon and that will be really good for him.
"If he can get a run of 90 minutes, then it is fair to look at his game and see where he is at. At this moment in time he has shown real glimpses of promise and has fitted in with the group really well."