The Reds changed the entire team at half-time in a relaxed return to action as a number of members of last term's FA Youth Cup-winning side pushed their claims at this level.
Brazilian Rafael Leao gave the visitors a seventh minute lead following smart passes by Oliver Norwood and Robbie Brady. Danny Drinkwater pounced on a defensive slip to stroke in a second, only for some sloppy play at the back at the other end to allow Sam Walker to pull one back soon afterwards.
Keepers Josh Ollerenshaw and Joe Coll made flying saves from Paul Pogba and Kristian Dennis respectively but Will Keane extended the lead, getting up after being flattened in the box to crash home the penalty. Ravel Morrison provided the icing on the cake by dancing through to show his class with a solo strike, the last kick of the game.
United 1st half: Jacob; Massacci, Giverin, McGinty, Fornasier; Brady, Norwood, Vermijl, Drinkwater, Lingard; Leao.
United 2nd half: Coll; M.Keane, Fryers, Brown, Thorpe; Pogba, Petrucci, Morrison, Cole; W.Keane, Cofie.