Brentford slipped to a derby day defeat as Leyton Orient came from a goal down to beat The Bees 2-1 in east London.
Carl Cort gave the visitors an early lead but Scott McGleish levelled it up and The Os won it thanks to a Danny Foster own goal.
After the first 25 minutes it looked as if the points would be coming back to west London, Brentford were a goal up and dominant.
But a tactical alteration from the home side allowed them to get a foothold in the game and level it up.
And they made the most of a misjudgement from Foster to take the win.
The Bees took the lead the first time they got into Orient territory - Sam Wood swung in a free kick from the left and Cort headed in at the near post.
The hosts had early efforts - Jimmy Smith shot well wide and Andros Townsend blazed an effort across the face of goal - but The Bees were on top.
Cort almost doubled the lead with a low volley after Cleveland Taylor had knocked back a Wood cross but Glenn Morris saved.
Wood came close with a fierce volley from 20 yards which flew inches wide but soon after Townsend switched flanks with right sided midfield player Jason Demetriou and Orient came back into it.
Demetriou's first impact after switching wings was to put in a cross which McGleish laid into the path of Ryan Jarvis, the striker got behind Mark Phillips and was brought down by the Brentford defender.
Andy D'Urso awarded The Os a penalty and booked Phillips but although McGleish's kick was firmly struck it went straight down the middle and Nicky Bull saved with his legs - Jarvis smacked the loose ball wide under pressure after a mini scramble.
The miss should have given The Bees a boost but it was the hosts that flourished - Phillips had to be alert to divert a Jarvis shot over the top but moments later Orient were level.
Demetriou swung in a cross, Tamika Mkandawire, who had stayed forward after the corner won by The Os after Phillips' block, headed down and McGleish acrobatically volleyed in from 14 yards.
Brentford pushed forward to try and regain the lead - Marcus Bean shot over from the edge of the box, Cort screwed a volley wide and a weak Taylor shot also missed the target.
And it continued in a similar vein after the break - a great run forward from Ryan Dickson lead to the left back finding Cort 10 yards out but the goal scorer chose to try and find Charlie MacDonald, who shot wide from a tight angle, rather than shooting himself.
Townsend fizzed a shot over from 25 yards and McGleish headed wide for the home side while Morris made a good save at full stretch from a Taylor volley.
The crucial moment came midway through the half when Townsend produced a brilliant run on the right and out over a cross that was begging to be headed in - unfortunately for Brentford after The Os strikers let the invitation pass Foster headed in at the far post.
With the lead secured Orient seemed content to sit on it and the last 25 minutes was all Brentford.
Taylor volleyed over, Myles Weston dragged a shot wide and Foster almost redeemed himself with a shot well saved by Morris after he exchanged passes with MacDonald.
Morris saved an O'Connor free kick and then held a looping header from Bean after a Weston cross was half cleared.
O'Connor blazed wide from the edge of the box after a Cort lay off but a goal could not be found and The Bees were beaten.
Leyton Orient: Morris; Cave-Brown (sub Purches h/t), Chorley, Mkandawire, Daniels; Demetriou, Smith, Summerfield, Townsend; Jarvis (sub Melligan 81 mins), McGleish
Subs (not used): Butcher, Ashworth, Pires, Baker, Scowcroft
Bookings: Daniels (51 mins), Purches (86 mins)
Brentford: Bull; Foster, Phillips, Bennett, Dickson; Taylor, Bean, O'Connor, Wood (sub Weston 67 mins); MacDonald, Cort
Subs (not used): Price, Wilson, Osborne, Blake, Saunders, Kabba
Bookings: Bean (28 mins) (fifth of season) (one match suspension - Stockport County (H) October 24), Phillips 32 mins (second of season)
Attendance: 4,781 (1,457 Bees fans)
By Chris Wickham