The game felt rather sluggish in the first half with neither team was able to test the opposing goalkeeper.
Danny Johnson did have one sniff of goal nine minutes into the match, after latching onto a loose pass. The O’s striker raced onto the ball before taking aim from 20-yards and curling a strike against the crossbar.
Orient failed to create a notable chance until the 36th minute. Jordan Maguire-Drew’s free-kick was nodded into a dangerous area by Jamie Turley, the visitors failed to clear, and Sam Ling capitalised – heading the ball home off the underside of the crossbar.
Danny Johnson doubled the advantage shortly after the restart. The forward did excellently to control, turn and volley into the net from the edge of the area, after being found by debutant Jordan Thomas.
The O’s had opportunities to put the game to bed – Maguire-Drew could only fire wide after being found by Lee Angol as Orient countered.
Brighton substitute Ben Wilson flipped the game on its head in the closing ten minutes. First smashing home from close range and secondly heading the ball past Sam Sargeant – seemingly setting up a penalty shoot-out to settle the tie.
Straight from kick-off, Lee Angol raced into the opposition box and won a penalty, which he volunteered to take. The forward stepped up and blazed the ball well over the bar.
Ross Embleton’s team had one more opportunity to steal the win at the end and Conor Wilkinson was the man in the right place. Brighton failed to defend yet another set piece and the Orient number nine smashed the ball past the goalkeeper to claim victory.
ORIENT: Sargeant, Thomas, Turley, Widdowson, Ogie, Ling (Clay 58’), Wright, Dayton (Wilkinson 64’), Sotiriou, Maguire-Drew, Johnson (Angol 58’)
SUBS: Vigouroux, Happe, Coulson, Judd
GOALS: Ling 36’ Johnson 55’ Wilkinson 90’
Brighton U21s: Rushworth, Cochrane, Gwargis, Roberts (Tsoungui 78’), Jenks, Crofts, Cashman (Vukoje 72’), Yapi, Dendoncker, Weird, Spong (Wilson 58’)
SUBS: Leonard, Furlong, Tanimowo, Talley
GOALS: Wilson 84’ 89’