Orient had their pocket picked by Tranmere Rovers in this FA Cup round one replay at Brisbane Road.
Ash Taylor scored in the 82nd minute with a strike at the far post after Stephen Purches failed to clear Shaleum Logan's free kick, conceded by Jason Demetriou.
It settled this cup tie which had never felt like a FA Cup occasion. That was due in part to the fact that only 1,514 people were watching.
Boss Geraint Williams threw on Adrian Patulea as a last desperate throw of the dice, hauling off Purches.
Orient had the ball in the net on 85 minutes after a goalmouth scramble actioned in by the hungry Patulea, but referee Andy Woolmer ruled out for a foul on Rovers keeper Luke Daniels.
Orient played well in the game, so losing it marks a low point in the season. The players left to jeers of 'What a load of rubbish' from the die-hard Orient fans who had braved the cold to come along.
That was perhaps a touch unfair, as Orient dominated possession for whole swathes of this game. Glenn Morris in goal hardly had his gloves warmed by shots all game.
But it was never obvious where Orient's goals would come from.
Adam Chambers continued his return from a calf injury by starting at the heart of midfield.
He was in the right place to keep an attack alive for his whole time on the pitch. The sight of him in action at each end of the pitch was a sight to warm the cockles on a bitter night.
Orient had two early shots from Jason Demetriou and Sean Thornton in the first five minutes, which was two more than the host's managed last week, in the whole first half against Hereford in the Johnstone Paint Trophy.
Orient started with refreshing purpose, keeping possession in the final third and pinging in crosses to the penalty box.
Rovers sat back and tried to soak up the pressure. One of the rare occasions when the game went into Orient's final third was when Demetriou, under pressure, ran the wrong way down the left flank.
On 32 minutes, McGleish turned his marker and shot from a tight angle at Rovers keeper Luke Daniels. An easy save, but the effort capped a prolonged period of pressure, started when Chambers stuck his foot in to intercept and keep the phase alive.
Meanwhile, Daniels' long passing looked laser guided at times. On 35 minutes, only the straining head of a Tranmere defender stopped his free kick from reaching McGleish at the far post.
McGleish was full of good touches in the first half. His cheeky backheel flick sped agonisingly wide on 43 minutes.
Glenn Morris did not have anything to interest him until the start of the second half when a shot whizzed high over the bar and into the Tommy Johnston south stand.
Charlie Barnett slightly warmed his gloves later on, with a tepid long range shot on 75 minutes after he caught out Chambers.
Ryan Jarvis replaced JJ Melligan ten minutes after the restart, and he had the first meaningful strike of this contest in the 66th minute when he lashed a shot at Daniels in goal from McGleish's flick on.
The tie was sliding towards extra time and penalties when Taylor popped up and burst Orient's FA Cup dream.
Morris, Purches Capt, Chorley, Mkandawire, Melligan, Chambers, McGleish, Thornton, Demetriou, Daniels, Scowcroft Jones, Ashworth, Jarvis, Cave-Brown, Pires, Smith, Patulea.
Attendance: 1,518, including 145 Rovers fans.
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