Despite being level at the break, the clash roared into life in the second period.
Dimitar Berbatov won and scored a penalty to equalise after Luis Garcia's goal, before Mark Gonzalez’s sublime free-kick and late strike earned the win for Kenny Dalglish’s side, ahead of September's return leg.
It was another fantastic occasion at the Theatre of Dreams, with the crowd welcoming back 17 great figures from United's past, along with their Liverpool counterparts.
FIRST HALF
The first half began with huge jeers from United supporters, who enjoyed Liverpool captain Jamie Carragher’s misplaced pass just moments after kick-off.