The home side took the lead two minutes before the break from the penalty spot, but Steven Gerrard's side were awarded a spot-kick of their own just before the hour mark.
The lively Fidel O'Rourke was brought down and Glen McAuley stepped up to make it 1-1.
A young Liverpool side then had some glorious chances to win it before Sunderland grabbed the winner three minutes from time following a set-piece.
Reflecting on the 90 minutes, U18s assistant manger Tom Culshaw told Liverpoolfc.com: "We were the better side and created some great opportunities but unfortunately we didn't take them.