BILLY Paynter's late header completed a smash and grab turnaround for lacklustre Rovers who were largely bossed by the Bees.
Paynter powered home a cross from Martin Woods five minutes from time to steal all three points from Dean Saunders' men.
Brentford took a deserved lead on the stroke of half time when a superb through ball from Adam Forshaw sent the superb Jonathan Douglas clear to clip a shot past Gary Woods.
The Bees dominated much of the game, controlling the middle of the park well as Rovers opted to defend from their own 18 yard line.
It took an absolute stunner against the run of play from David Cotterill for Rovers to draw level.
Picking up the ball 30 yards out, Cotterill found space and smashed an effort into the top right corner, giving Bees keeper Simon Moore no chance.
The goal lifted Rovers and a home support forced to watch their side spend the majority of the game chasing the ball.
Clearly gutted to find themselves level, Brentford lost concentration and Paynter was completely unmarked ten yards out as he sealed the win.
Saunders has lined up a defender from a Premier League club to come in on loan after suffering another loss in the rear guard.
He was forced to rejig his back line during the game after Shelton Martis was withdrawn with a groin problem with James Harper filling in at left back.
Rob Jones was forced to play on with a dislocated thumb due to the lack of defensive cover on the bench.
Saunders also revealed that former Coventry City and Nottingham Forest midfielder Sammy Clingan has been training with the club.