Orient got among the goals with a strong attacking display today sure to help banish memories of the new year's day drubbing.
Boss Russell Slade's side made a top scoring start to 2011 with strikes by Jimmy Smith on 41 minutes, and Alex Revell, Paul Jose M'Poku and then Jonathan Téhoué in an event packed match.
Smith headed Orient into a half time lead on 41 minutes from Dean Cox's cross. Smith had earlier seen an effort cleared off the line.
The hosts improved after making a slow start when the U's had dominated proceedings but lacked cutting edge.
Then hitman Alex Revell opened his account for the year just four minutes into the second half when he capitalised on a dreadful error by Matt Heath who made a mess of his back pass.
Revell finished with a cool finish under keeper Ben Williams.
Orient were strong in this game as the U's faded but got back into the contest through defensive errors.
But Ben Williams in the opposition goal had a tough time between the sticks, letting Téhoué's late winner get past him.
O's stopper Jamie Jones suffered an error of his own on 69 minutes, when he spilled the ball inside his own box for Anthony Wordsworth to tap in and cut Orient's lead in half. 2-1.
But Spurs loanee M'Poku settled nerves set jangling by that when his blast re-established Orient's two goal cushion on 75 minutes. It was a fine finish by the Spurs lad for his first league goal.
The U's then got back yet again into the game on 81 minutes when Ian Henderson just strolled through the heart of Orient's non-existent defence for a simple finish and goal.
It was a major lapse by Orient, but one which their attacking verve neutralised in this game.
Super sub Jonathan Téhoué showed plenty of that when he settled the match with four minutes left with a rasping drive too hot to handle for Williams. 4-2.
Orient were much improved after the drubbing dished out to them by Brighton on new year's day.
The result against one of League One's stronger side buoys spirits in a close fought campaign.
Jones, Omozusi, Whing, Chorley, Cox (M'Poku), Dawson (capt), McGleish, Revell (Téhoué 68), Daniels, Spring (Chambers), Smith.
Unused subs: Butcher (gk), Brown, Cestor, Walker.
Attendence: 4,339 including 708 U's fans.
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