Larnell Cole's opener was soon overturned by Jordon Ibe, Adam Morgan and Fabio Borini, only for Jesse Lingard to pull one back before the interval. Despite plenty of pressure by Warren Joyce's side, Borini wrapped things up towards the end.
In a breathless first half, Lingard had already flashed a shot wide when he was involved in the move that led to the opening goal inside seven minutes. The England Under-21 international showed good strength to hold off Ryan McLaughlin and the ball was fed to Cole via Belgian duo Adnan Januzaj and Marnick Vermijl. The man who scored a hat-trick against the Merseysiders in last season's semi-final found the net at the second attempt after his initial shot was blocked.
Liverpool's response was swift and purposeful as Ben Amos was forced into a first-class save to thwart Borini and, moments later, Ibe ran through the defence to find the bottom corner with a clinical low drive. Only the bar denied Jack Dunn and a rare slip by Michael Keane let in Adam Morgan for another finish out of the top drawer.
A debatable free-kick in the 20th minute allowed the visitors to move further ahead when Davide Petrucci was harshly penalised for a sliding tackle. Borini smashed the set-piece goalwards and the swerve denied Amos to make it 3-1. Craig Rodden blasted wide as United appeared rocked by the turnaround but Januzaj tried to regain some composure with a splendid turn and run that led to the first booking for Joe Maguire's crude foul.
Januzaj was inevitably involved when he and Cole helped tee up Lingard for a splendid low drive to reduce the deficit with a lovely goal. Captain Tom Thorpe then headed into the side-netting