A goal late in the first half from Swindon Town was enough to condemn Brentford to defeat in Wiltshire.
The Bees survived an early Swindon penalty, superbly saved by David Button, but Louis Thompson scored in the last seconds of the first half to put the hosts in front.
Brentford may have considered themselves unfortunate to be behind and pressed for a leveller after the break.
But they had Adam Forshaw sent off in the second period as they headed back down the M4 with nothing to show for their efforts.
Swindon started with three central defenders and three in an attacking line.
Unlike many teams, they tried to take the game to The Bees, not content to let Brentford have the ball.
They pressed Brentford intensely for long periods, trying to win the ball in dangerous areas.
They also showed attacking intent when they had the ball and looked to create chances.
They had a good one early on from a Jay McEveley free kick that just eluded three men arriving at the far post.
The home side should have gone ahead inside the first 15 minutes when they were awarded a penalty after Alex Pritchard goaded Alan McCormack in to a challenge and then went down when it came.
Referee Brendan Malone pointed to the spot and Swindon striker Michael Smith took the responsibility.
His penalty was low and hard to the right of Button but the Brentford goalkeeper got down and turned it away.
Tony Craig made a vital block from the resulting corner, keeping out a Jack Stephens volley, as the home side piled on the pressure.
But the game had not been one-way traffic.
While the home side had started quickly, Brentford had attacking intent themselves and with Clayton Donaldson regularly in space on the right, they stretched the home side.
They had early chances – Craig flicked a header over the bar from a corner before a low McCormack cross just eluded Marcello Trotta.
A deflected Donaldson effort looped just over the bar and, soon after Swindon’s spot kick, Jonathan Douglas headed a Jake Bidwell free kick against the outside of the post.
Brentford started to get on top of the entertaining game as it reached the one quarter mark.
The best chances were falling to Trotta.
He headed a Donaldson cross over and then, after he combined with Donaldson to win the ball and then got back on to a Toumani Diagouraga pass, a low shot was saved by Wes Foderingham with his legs and rolled inches wide.
Trotta had an even better chance when he picked up a Donaldson pass and appeared to be clean through but he failed to get the ball out of his feet and Stephens got back with a recovery tackle.
Button saved a McEveley shot and Trotta volleyed across from McCormack wide at the near post.
The hosts went ahead with a goal that Brentford will want to forget.
Button drilled a pass at Douglas and as the midfield players controlled it at throat level he was robbed by Louis Thompson, the Swindon man raced in to a massive gap and slotted home.
Pritchard and Massimo Luongo had shots blocked as Swindon pressed for a second before half time.
The home side had a lead to defend in the second period and seemed to take a slightly more passive approach to the game.
Their wide players dropped back a few yards so a 3-4-3 became more of a 4-5-1.
Brentford pressed forward and Swindon were happy to invite them, looking to break in numbers when they could.
Nathan Byrne could have given them home side breathing space early in the second half when he got in behind on to a Nathan Thompson pass, Button raced out and the lob was put up but the ball bounced just wide.
At the other end, Trotta was just unable to head in a McCormack cross and substitute George Saville forced Foderingham in to a superb low save with a shot from 20-yards that the keeper tipped away to his right.
Foderingham then rushed out to beat Alan Judge to a ball forward while, at the other end, Byrne curled in a shot from 20 yards that Button saved.
The game appeared to have swung Swindon’s way midway through the second half when Forshaw was shown two yellow cards in the space of 90 seconds.
Neither was really arguable and Brentford had to play the final 24 minutes a man down.
The red card seemed to spur The Bees on and they had the better of the later stages.
Bidwell came within a whisker of equalising when he got on to an inside pass from Donaldson but his toe-poke rolled inches past the post.
Donaldson headed a McCormack cross wide and substitute Stuart Dallas had a shot blocked.
McEveley shot over the bar for the home side before Brentford had a great chance to equalise.
A corner flew across the box and reached James Tarkowski on the far side, eight yards out, but he sliced a shot wide.
In the dying seconds Craig headed a long throw over the bar as Brentford pushed in vain for the equalising goal.
Swindon Town: Foderingham; Stephens, Archibald-Henville, Rossi-Branco (sub Hall 90 mins); N. Thompson, L. Thompson, Luongo, McEveley; Byrne, Smith (sub Gladwin 79 mins), Pritchard (sub Storey 85 mins)
Subs (not used): Belford, Waldon, Barthram, Cox
Bookings: Stephens (19 mins), McEveley (23 mins), Rossi-Blanco (55 mins), Byrne (90 mins)
Brentford: Button; McCormack, Tarkowski, Craig, Bidwell (sub Grigg 87 mins); Diagouraga (sub Saville 56 mins), Douglas, Forshaw; Donaldson, Trotta (sub Dallas 65 mins), Judge
Subs (not used): Lee, Yennaris, Dean, Reeves
Bookings: Craig (14 mins) (seventh of season), McCormack (49 mins) (ninth of season)
Sent Off: Forshaw (66 mins) (second bookable offence)
Attendance: 9,342 (1,906 Bees fans)
By Chris Wickham