Connor Davies headed wide on four minutes but he then gave his side the lead shortly after. Tom Morgan's flick on found Davies and his perfectly placed lob sailed over the keeper and into the net.
Morgan then almost intercepted a back pass but the keeper's clearance struck him and bounced away to safety. But a minute later, Longwell Green equalised when Nathan Hughes curled in from the edge of the penalty box.
Gary Shorney hit a rising shot over the crossbar before Ali Bamford twice went close inside a minute. His inswinging free kick eluded everyone before bouncing down and over the bar. He went even closer with a volley from inside his own half that had the Longwell Green keeper desperately scrambling back to save.
Three minutes before half time, Longwell took the lead with a bullet header from Lewis Simpson that went in off the crossbar and early in the second half, the visitors looked more likely to score with Josh Dempsey diving full length to save twice.
On the hour, Gary Shorney levelled matters with a low left foot effort that squeezed in at the post. O's then made three subs including a first team debut for 16-year-old Alex Robertson and on 75 minutes, grabbed the winner. It was Connor Davies again, this time with a superb solo goal cutting in from the right wing and smashing home a left footed shot into the far corner.
Team:
Dempsey, Welling, Bamford, Richards, Greenwood, Davies, Abraham, Shorney, Parker, Williams, Morgan.
Subs (all used)
Bernard, Winstone, Robertson