ORIENT ultimately did not have enough fuel in the tank to hold off a Norwich City side who were clinical in the final stages of an engaging contest.
Chris Martin broke the deadlock on 74 minutes when he slotted home from a Korey Smith cross.
The hosts doubled their lead moments later when Grant Holt grabbed number two, Michael Spillane added a third with a ferocious half volley.
Substitute Jamie Cureton left no doubt that the points will go to Carrow Road when he scored in the depths of injury time.
Until the late goals Jamie Jones had given a goalkeeping master class and it looked likely that the O's would depart East Anglia with a point.
Indeed, the Orient stopper showed extreme bravery when collecting a ball from Holt he crashed into the bulky frontman and laid on the pitch for several minutes while being treated by paramedics.
Fortunately, for the O's he remained able to carry on but the east Londoners had to make do without the services of JJ Melligan who was sent off for violent conduct after tempers threatened to boil over.
The home support barracked former Ipswich striker James Scowcroft throughout and were incensed he did not receive his marching orders for an earlier robust challenge.
Orient started the contest well with plenty of pace and passing.
Andros Townsend, who started ahead of the injured Jason Demetriou who was on the bench, picked up where he left off against Millwall by running at the City defence during the early stages.
Indeed, he had the first meaningful effort of the match but his shot was well held by Declan Rudd.
However, Norwich were soon on the attack and captain Tamika Mkandawire was alert when he made a saving tackle to deny City but the hosts gained a corner which was again dealt with by Mkandawire.
Townsend again gave the City defence nightmares when he went at full tilt and set up Luke Summerfield whose cross was cleared - but only as far as Charlie Daniels who hit a rasping shot at Rudd, who really had to stretch to save the ferocious effort.
Again Norwich countered and paceyIrish winger Wes Hoolahan reduced the Orient defenders' legs to jelly with a twisting run but the City attack were unable to connect with his cross.
Hoolahan then had a great chance to give the hosts the lead when he was sent clear. Orient's back line thought he was off side but the flag stayed down. He raced towards Jones and passed to Simon Lapin whose shot magnificently saved by the O's stopper.
City then attacked through lanky striker Grant Holt but the former Nottingham Forest hitman's effort was headed cleared by Andrew Cave-Brown.
Jimmy Smith went into the referees book for unsporting conduct. Rudd's long punt of a free kick was gathered by Holt who played in Hoolahan but the winger's cross evades City forwards and is cleared.
The hosts attack again with Holt's shot deflected out for a corner but the East Anglians are unable to capitalise on the opportunity.
Fifteen minutes before half time Jones is called into action again. A dangerous cross by Holt is headed by Paul McVeigh but he can only direct it straight at the O's keeper.
Jones saved again from a deep Spillane cross with Holt charging in.
But the O's hold and the game is goalless at the half time break.
Norwich began much more purposely after the restart and do everything but score. It seems it is not their day.
Geraint Williams brought on Demetriou and Scott McGleish who replace the lively Townsend and Scowcroft respectively.
But neither were able to prevent Norwich from eventually making a breakthrough and winning the game at a canter.
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