Orient fell to their first defeat on the road as two goals inside three second half minutes helped Notts County pick up their maiden home league win of the season.
After a goalless first half, a header from Jonathan Forte and a fierce strike by Jon Stead put the Magpies in the box seat, though Louis Laing was shown his marching orders soon after for two bookable offences.
Paul McCallum pulled one back with four minutes to go, but it proved to be a mere consolation as Aaron Collins netted a stoppage-time third to seal victory for John Sheridan’s side.
The O’s made one change from the side which lost out last weekend to Yeovil Town with Jay Simpson starting in place of Jordan Bowery, while there was a place on the bench for new signing Jens Janse.
Orient started on the front foot with the early possession and it was that man Simpson who was straight into the action. Strike partner McCallum knocked the ball into the former Arsenal man, and despite having his back to goal, flicked the ball goalwards, only to see it fall just wide.
Up the other end Stead put in a teasing cross, but Yvan Erichot was on hand to shield the ball from the onrushing Jonathan Forte.
It was certainly proving to be end-to-end, and on the O’s next assault forward Cornick’s teasing delivery was pushed behind for a corner.
Simpson continued to be in the action and he went even closer for the second time in the space of the opening 15 minutes when taking a touch on the edge of the area before firing wide of the post, and then just poking a Weir through ball wide.
The game continued at a frenetic pace and Stead was inches away from breaking the deadlock for the Magpies on 17 minutes, only for Tom Parkes to intervene and put it behind for a corner.
Simpson was the main man for the O’s and it was fair to say Stead was the thorn in the O’s defence. Nicky Hunt, was the first to produce a fine block to deny the forward, before Cisak did well to keep another effort at bay.
Liam Kelly has been less prolific in front of goal of late having previously notched in three successive league games, and was teed up by McCallum after 27 minutes but the midfielder directed his shot off target.
The game inevitably would go through a quiet spell given the fast paced opening, but as the half drew to a close Parkes got in another fine block to deny Tootle before in stoppage time Simpson saw his effort on the turn saved by Adam Collin.
Neither side made changes at the break and the first chance of the half came the way of the Magpies and Stead as he headed a cross wide of the mark, and then Cisak come out well to smother the ball at the feet of Forte.
However, Forte was to put the hosts in front when a ball in from the right by Matt Tootle on 53 minutes found the unmarked striker and while Cisak got a great hand to it, it was deemed to have gone over the line.
And then one soon became two, just a couple of minutes later as Stead cut in on his left foot and left fly from 20 yards and past the despairing dive of Cisak.
Ulrich Nnomo came on to make his O’s debut in place of Harry Cornick just after the hour mark, while Simpson’s free-kick from 20 yards sailed over the bar.
The hosts then had penalty appeals waved away when Erichot and Aaron Collins tangled in the box, before the O’s mounted an attack where Simpson was hauled to the ground by Laing. Already on a booking, referee Brendan Malone showed the defender a second yellow and the O’s would finish the game playing against 10 men.
A double sub saw Sandro Semedo and Jordan Bowery on for Massey and Simpson respectively with Bowery going close almost instantly as he headed Hunt’s delivery goalwards, however, it was easy for Collin to hold in the Magpies goal, while Kelly had gone close earlier when Collin was forced to tip a shot behind for a corner.
With the O’s in search of a goal gaps would inevitably come at the back and Collins jinked one way then the other as he tried to get the better of Parkes and Erichot. The substitute was able to get a shot away but it curled over the bar.
McCallum, shown a yellow card for a late tackle on Duffy, did give the O’s a lifeline on 86 minutes when he headed in Bowery’s ball across.
Chances came the visitors way to force a leveller as Kennedy fired just wide and then Nnomo saw an effort hit the side netting.
But as Orient pushed forward in six minutes of stoppage time they were dealt the killer blow when Collins mounted an attack, beat the attention of Nnomo and Erichot to slot past an onrushing Cisak.
Notts County: Collin, Tootle, Dickinson, Duffy, Hollis, O’Connor (Richards 85), Forte (Oliver 72), Milsom, Laing, Rodman, Stead (Collins 59).
Subs: Loach, Campbell, Burke, Aborah
Goals: Forte (53), Stead (55), Collins (90+2)
Booked: Duffy (45), Laing (63), Milsom (72)
Sent Off: Laing (70)
Leyton Orient: Cisak, Hunt, Erichot, Parkes, Kennedy, Massey (Semedo 72), Kelly, Weir, Cornick (Nnomo 62), Simpson (Bowery 72), McCallum.
Subs: Sargeant, Palmer, Atangana, Janse.
Goals: McCallum (86)
Booked: McCallum (78)
Attendance: 4,289 (476 Leyton Orient supporters)
Referee: Brendan Malone.