First Division Orient scored the only goal at Carrow Road to put the Canaries out of this years FA Cup.
Jimmy Smith who had a loan spell with City when on Chelsea's books scored early in the first half and despite dominating the possession the home side's finishing lacked any cutting edge.
Paul Lambert, having yesterday dismissed the speculation linking him with the vacant Burnley manager's job, made six changes to the side that drew 1-1 at Middlesbrough on Monday. Keeper John Ruddy, defenders Michael Nelson and Simon Lappin, Andrew Crofts and Grant Holt all dropped to a bench of experienced first-teamers. Owen Tudur Jones was left out of the 18 man squad altogether.
But Lambert still named a very strong starting line-up including a recalled Wes Hoolahan, who himself has recently been the subject of much speculation about his Norwich City future. That speculation was put to bed after the game when it was confirmed that Hoolahan has agreed a contract that should keep him at Carrow Road until 2014.
In a lively but even start, City came closest first when Ben Chorley so nearly put Chris Martin's ball into the area for Aaron Wilbraham, into his own net. While the Londoner's had a shot by City ex-loanee Jimmy Smith saved by Declan Rudd, making only his third start of this season.
Orient, moving the ball on the floor, won the game's first corner in the 19th minute. From that they took the lead to stun the home crowd. Taken short, winger Dean Cox then lifted the ball to the back of the area, where Smith put a powerful header past Rudd.
The Canaries responded by continuing to play their patient passing game and pressing the visitors back into their own half. They were rewarded with their first corner and although Fox's delivery did find Wilbraham, the City striker couldn't get any power on his header.
Elliot Omozusi, another Orient player that was on loan at Carrow Road when at Fulham, was forced off in the 26th minute by injury and was replaced by Andrew Whing.
The home side finally made the Orient keeper work in the 38th minute when Russell Martin's shot was blocked and fell kindly for Hoolahan, but Jones got down low to smother the Irishman's goal-bound shot.
As the half drew to a close, Wilbraham and Leon Barnet both showed a lack of composure in front of goal when they had opportunities to get City back on level terms.
HALF-TIME: City 0 Orient 1
Neither side made any change at the start of the second half, as City attacked their favoured Barclay end.
The home side carried on where they left off before the break, dominating the possession with Anthony McNamee attempting to make the most of his rare start. However, the ex-Swindon winger's final ball so often lacked any real precision, much to the disappointment of the 16,000 home fans!
Despite controlling the game, the City boss decided in the 64th minute that it was time for a change and inject the fresh legs of Lappin and Holt as his side desperately searched for that elusive equaliser. Adam Drury and Wilbraham were the players to make way.
And just six minutes later he threw his last roll of the dice, replacing Chris Martin with the more pacey Simeon Jackson.
An illustration of just how much the Canaries were controlling the outfield play without hurting the opposition, came in the 75th minute when Paul-Jose M'Poku had Orient's only shot of the second period of play!
David Fox was the next home player to attempt to get his side back in the game, when he collected Whing's clearance of Russell Martin's cross, but he could only put his shot wide of Jones left hand upright.
In the final ten minutes of the game, more woeful crosses from McNamee, Lappin and Fox just added to the home fans' frustration. Russell Martin's frustration got the better of him and referee Dean Whitestone produced the yellow card for his 87th minute foul on M'Poku.
Holt had the last chance to retrieve something for City, when deep into the four minutes of added time, he could only only head over Hoolahan's corner - City's tenth of the game.
FULL-TIME: City 0 Orient 1