Second-half goals from David Mooney and Shaun Batt saw League One leaders Leyton Orient deal another blow to Brentford's promotion hopes.
Mooney kept his cool to open the scoring from the spot before Batt came off the bench to seal victory late on as the O's continued their perfect start and extend their lead over the Bees to a massive 12 points.
The hosts had started well, with Harlee Dean heading wide, while the Bees defender also had a penalty appeal waved away when he went down under pressure from Nathan Clarke.
The Bees had a let off on 20 minutes when Moses Odubajo crossed for Mooney, but the Orient striker planted his header over the top from six yards.
Martin Fillo headed straight at Jamie Jones, while Clayton Donaldson tested the O's keeper shortly after as the Bees continued to threaten.
Kevin Lisbie had a tame effort cleared off the line by Martin Taylor, and fortunately for the Bees, Mooney blasted the rebound over as the sides went in level at the break.
Donaldson fired over from distance at the beginning of the second half, while Clarke blocked Tony Craig's goalbound effort from point-blank range.
However, it was the visitors who took the leader against the run of play.
Shaleum Logan was penalised for a tug on Mooney in the box, and the Orient man picked himself up to fire past Richard Lee from the spot.
Things almost went from bad to worse for the Bees moments later, but Odubajo's fizzing drive was deflected inches over.
The O's did double their lead on 85 minutes when Batt outpaced the Brentford defence before slotting past Lee to seal victory.
BEES: Lee, Logan, Taylor, Dean, Craig, McCormack (Dallas 74), Diagouraga, Forshaw, Fillo (Teixera 69), Donaldson, Grigg (Trotta 74).
Subs (not used): O'Brien, O'Connor, Reeves, El Alagui.
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