Nigel Spackman will have to wait until at least Saturday for his first win as Millwall boss but on this evidence it can't be too far away.
A Lee Steele strike in first-half injury-time followed by a Gary Alexander finish 12 minutes from the end might have given Martin Ling's men the points but that only tells half the story.
As starts go it was a stinker for The Lions with Tony Craig seeing red for apparently wafting a dangerously high foot at Shane Tudor in the fourth minute, a decision which left the 1,400 Millwall fans in Brisbane Road bewildered. Spackman immediately switched Tom Brighton to left back with Saturday's scorer Darren Byfield working as the lone striker and Marvin WIlliams pushing up in support.
But things got worse for the visitors midway through the first half when Byfield had to be replaced by Poul Hubertz. The former Gillingham striker went down in a heap after a challenge on the touchline and left the pitch on a stretcher as the MIllwall bench wondered what else could go wrong.
They almost got their answer just before the break when Orient thought Steele had given them the lead only for referee Lee Probert to blow for a foul on Pidgeley. But it was only a brief reprieve as the home side took the lead in first-half injury-time when Zak Whitbread's clearance was intercepted by Michael Simpson. He fed Steele down the left who drove home at Pidgeley's near post.
Millwall almost hit back immediately when Derek McInnes laid a quick ball into Marvin Elliott's path but his first-time effort flew just wide. They left the field at half time to a standing ovation from the visiting supporters, the referee was given shrift of the very shortest kind.
Whatever Spackman said during the break seemed to have an effect and the visitors were left cursing their luck twice in the space of a minute just before the hour-mark. First Williams squirmed through the Orient defence only to see Garner beat away his snap shot. The ball flew out to Hubertz but his curled effort was deflected behind for a corner. Neal Ardley swung the dead ball plum on the head of Richard Shaw but his bullet effort was smothered low by the Orient keeper.
Spackman sent on Filipe Morais - dropped for Ardley - and Chris Hackett, for McInnes and Williams during the last half hour. And Morais almost made the perfect introduction with a 25-yard screamer which flew past the post with Garner beaten.
Then Pidgeley kept out a point-blank Shane Tudor effort to keep the visitors in the game, but moments later Alexander swept home Tudor's low cross to wrap up the points for Orient. Right at the death Hackett pounced on Clayton Fortune's awful back pass but shot wide with only the keeper to beat - it was that kind of night.
Leyton Orient: Garner, Lockwood, Simpson, Fortune, Mackie, Tudor, Easton, Alexander, Steele (Ibehre 85), Keith, Tann.
Subs not used: Barnard, Morris, Partridge, Corden.
Millwall: Pidgeley, Ross, Craig, Elliott, Whitbread, McInnes (Hackett 63), Byfield (Hubertz 23), Brighton, Ardley, Shaw, Williams ( Morais 53)
Subs not used: Robinson, Day.
Bookings: Fortune, Lockwood (Leyton Orient)
McInnes, Williams, Hubertz Sent-Off: Craig (Millwall).
Referee: Lee Probert
Attendance: 6,142 (1,384 away)