A Frenchman gatecrashed the East London knees up to bring the rampant Daggers their first win of the season.
And well deserved it was too, following a lively display that provided rich entertainment for a bumper 4,000 plus crowd.
Romain Vincelot got the goals that clinched the three points and defensive strong man Scott Doe walked away with the man-of-the-match award. But it would be unfair on the rest to pick out individuals from a solid team performance in which everyone played a big part.
Lessons from the previous Saturday, when they tossed away a two goal lead against Tranmere, had clearly been learned. Fans well used to watching the Daggers do it the hard way knew they could take nothing for granted when they went two up early in the second half.
Orient are a better team than Tranmere and Vincelot's second strike gave them 40 minutes to get back into it. But this time the Daggers stayed strong and stuck together to see the game out - although they did have a couple of scares along the way.
Vincelot gave the Daggers the start they had dreamed of by putting them ahead in the eighth minute. He surged powerfully into the box to meet a deep cross from Danny Green with a header into the roof of the net That ball split the Orient defence and Vincelot made sure it was not wasted.
Green threatened himself soon afterwards when he linked up again with Vincelot. But this time the Frenchman's return ball was over hit and the O's got it away. At the other end Matthew Spring had Tony Roberts moving smartly to get to a snap shot from 20 yards.
Vincelot featured again when he created an opening for Gavin Tomlin. But smart defending meant the ball was deflected for a corner. Green maintained the Daggers pressure by firing a volley over, then the lively Tomlin dragged a left foot effort wide.
Orient were mainly on the back foot and Doe proved in commanding form whenever they did threaten. Abu Ogogo also made his mark with a magnificent tackle to rob Spring as he got ready to pull the trigger. The full-back damaged himself with that brave challenge and was replaced by Will Antwi for the second half
Scott McGleish fired a good chance wide after a long ball sent him clear and Roberts made a superb reflex save from a close range header.
Scott had another good chance for the Daggers, but took too long on the ball and was knocked off it.
Vincelot, who struck early in the first half, did it again after the break to double the Daggers lead. And again the goal came from a header after skipper Mark Arber nodded back a corner from Green. That had the Orient defence on the wrong foot and the French midfielder swooped to apply the finishing touch.
Scott came close to adding a third with a venomous 30 yarder that smashed against an upright with O's keeper Jamie Jones little more than a spectator.
Orient changed their formation and played with three men up in a bid to get back in the game. Doe produced a brilliant block when he threw himself in front of an effort from Adam Chambers. But the man of the match almost went from hero to zero when he had Roberts going full length to keep out a misplaced back header.
Roberts also saved well from Alex Revell, but the Daggers were in no mood to give anything away and dug in for a hard earned, and thoroughly deserved victory.
Att: 4195 (1199 Leyton Orient fans)