The Black Cats took the lead through a Jordan Laidler free-kick early on and held the advantage until Anton Forrester levelled just before the break.
The game looked to be heading towards a draw until Forrester popped up five minutes from time to head in the winner.
The youngsters haven't won since the 2-1 win over Spurs back on December 10th
Kevin Ball (talking on the SAFC official website): “It was a frustrating night because we were beaten despite doing some really good things in the game.
“We started the game really well and deserved to go ahead. Yes, Jordan’s free-kick took a deflection but it was nothing less than we deserved.
“I was pleased with them in the build-up to half time, although the goal we conceded should have been defended better.
“It wasn’t much of a game [in the second half] and neither team created much.
“We were heading towards a fair draw only to concede from movement following a free-kick we didn’t need to give away.
“I don’t think we deserved to lose; we did well in the game.”