Thwaites then found himself in acres of space before blazing over the bar as Fletcher's young side attempted to get back into the game again, but there was still plenty of twists to come.
Obi stole a march on skipper Finlay Holcroft, racing through on goal, similar to how he did in our last Youth Cup outing at Old Trafford, before taking his time to poke the ball past Cowan to make it level again.
And just moments later, Gabriel's driving run forward allowed Brown space over on the right of the box, before he applied the required finished to turn the tie around, smashing home at the near post.
Chido then almost added a fourth soon after, but perhaps selfishly went alone when better options were to his right, seeing his shot saved by the Black Cats goalkeeper.
The game then petered out somewhat as United opted to hold what we had, with Dinsdale late drive easily saved by Byrne-Hughes, as three added minutes played out.
But it's progression again for our Academy side, who will face the Eagles for a place in the FA Youth Cup final at Selhurst Park, with a date and time for that game to be announced.