A dramatic late winner from David Mooney sent Leyton Orient into the quarter-finals of the FA Trophy after a rollercoaster second half saw them ultimately prevail 4-3 at Dover Athletic.

After George Elokobi had given Justin Edinburgh’s men the lead at the interval, a quick-fire burst from Macauley Bonne and Matt Harrold appeared to have the O’s firmly in control after opening up a 3-0 lead early in the second period.

But the hosts, who are 11 places higher than their opponents in the National League table, came roaring back and had levelled the game going into the closing stages, before substitute Mooney clinched a place in the last eight in injury time.

Edinburgh made three changes to the side that won at Halifax Town in midweek, with Joe Widdowson, Lamar Reynolds and Harrold all coming into the starting XI, while new signing James Brophy started his second spell with the E10 club on the bench.

After Dean Brill had been forced into a couple of good early saves, Harrold forced Dover keeper Mitch Walker into a fine stop at the other end after being played through by Ebou Adams.

Both sides continued to trade chances but it was the O’s who made the breakthrough when Elokobi headed home a Jobi McAnuff corner.

Brill had to make another smart stop to tip Nortei Nortey’s long-range effort behind, but the O’s nearly double their lead just before the break when Harrold saw his effort cleared off the line by Josh Passley.

But when Orient’s second goal did arrive after the restart it was memorable as Bonne picked up the ball 30 yards out and found the top corner in superb fashion.

And two goals were to become three soon after when Harrold beat Walker after Elokobi had headed the ball to his teammate.

But if the visitors thought they home and dry they were in for a rude awakening as Dover pulled one back quickly, with Ryan Bird diverting home a Mitchell Pinnock shot that was going wide.

After Anthony Jeffrey rifled into the side netting from 20 yards, the game went through a quiet spell before Bonne could have made sure of a place in the next round when he was put through by Harrold, only to be denied by an excellent stop from Walker.

Dover duly set up a grandstand finish with nine minutes remaining when Pinnock beat Brill with a superb lob from 25 yards after a Josh Coulson clearance could only pick out the Athletic player.

And the turnaround was completed moments later when Bird tapped home after a Kadell Daniel shot was saved.

It looked like both sides would have to try again in a replay, but with time running out Brophy played in fellow substitute Mooney and he took a touch before lifting his finish over Walker to spark jubilant scenes among the O’s fans.

Leyton Orient: Brill, Caprice, Coulson, Elokobi, Widdowson, Adams, Clay McAnuff, Reynolds (Brophy 67), Harrold (Mooney 82), Bonne. Subs not used: Sargeant, Koroma, Happe