Stuart Dallas came off the substitute’s bench to smash home a stoppage time winner as Brentford came from behind to beat high-flying Derby County at Griffin Park.
The visitors flew out of the traps, looking to prove their promotion credentials.
They had a number of chances before Chris Martin put them ahead just before the half hour.
But Brentford started to get back in to the game as the first half wore on and Andre Gray equalised early in the second.
It looked as if the spoils would be shared, especially when Gray hit the post later on, but Dallas, only just back from injury, lashed home the winner four minutes in to stoppage time to ensure the team that started to day top of the Sky Bet Championship left West London empty handed.
Derby could have been ahead inside five minutes when Simon Dawkins fired in to the side netting after making the most of a ricochet and when the wide man then put Craig Forsyth in, David Button had to get down well to his right to push a low shot away from danger.
Martin then curled over for the visitors, who had much the better of the first ten minutes.
Brentford started the game with Toumani Diagouraga and Jon Toral alongside Jonathan Douglas in the centre of the midfield.
Once the trio started to link up, hassle Derby and get Brentford posession in decent areas, The Bees had a foothold in the game.
Jota had a couple of chances to open the scoring, seeing a shot blocked after a nice turn and then heading a drilled Alan Judge cross wide.
But Derby had potent attacking threat.
The movement of Dawkins and Martin, in particular, on the left side was posing Brentford a number of problems.
It was no surprise the opening goal of the afternoon came from the visitors down that side.
Cyrus Christie robbed Judge as Brentford looked to break and quick as a flash defence was turned in to attack – Forsyth provided the overlapping run on the left and his cross was swept home by Martin, a near post effort rolling in off the far post.
Derby had gone close moments earlier when Richard Keogh headed a corner down and Martin fired across the face of goal but Douglas cleared and nearly set up a breakaway goal when Gray fed Judge but Omar Mascarell got back to make a recovery tackle.
Christie made a fine recovery tackle soon after to prevent Douglas getting on to a Gray pass ten yards out and his next involvement was to make the tackle for the opening goal.
Judge had a low shot blocked as Brentford tried to respond immediately but Jeff Hendrick nodded Martin through on goal soon after only for the striker to fail to control.
Mascarell had a shot deflected wide as did Hendrick but Brentford started to take the upper hand as half time approached.
They pressed Derby in to defensive mistakes, starting higher up the pitch, and Diagouraga came to the fore.
The Bees came close to an equaliser when, on the break, Jota fed Toral but the chipped effort flew just wide.
Toral went close again just before the break with a volley from a Jota corner that was blocked inside the six-yard box but The Bees went in at half time behind.
That did not, however, last long after the break.
The second period was less than four minutes out when Douglas picked up a loose ball in midfield and released Moses Odubajo – the right back, moved to a deeper in place of the injured Alan McCormack, hared 50 yards up the pitch before releasing to Gray and the striker expertly placed the ball past Jack Butland and in to the corner from 20 yards without a second touch or thought.
Griffin Park was alive – Johnny Russell had shot over for the visitors before Gray’s goal but Brentford had all the second half momentum.
Toral brought the fans to their feet with a sublime piece of skill that almost got him through, Harlee Dean had a shot blocked and Diagouraga’s follow-up was also blocked as Brentford pressed.
Derby were rattled, Keogh and Dawkins were cautioned by referee Carl Berry when forced in to illegal means to stop marauding Brentford attacks, and the visitors introduced Will Hughes and Jordan Ibe to try and change the flow of the match.
Martin headed wide and Dawkins, in his last action, got to a long ball before Button only to take heavy touch and put the ball out.
Substitute Alex Pritchard had a shot blocked for The Bees and a Douglas header was saved as Brentford continued to hold the upper hand.
And they should have been ahead midway through the second half when Judge picked up a long pass from Button and chipped in a cross that Gray headed against the post from eight yards.
Ibe almost punished The Bees immediately on the break but Button saved his low shot and the Brentford goalkeeper kept out a Martin header soon after.
With both teams looking for the winning goal it was set up to be a thrilling final 15 minutes.
Ibe cut inside and shot wide before Mascarell blasted over as Derby attacked but stoppages for head injuries to Tony Craig and then Keogh halted the flow.
Christie had a shot blocked before Dallas struck.
Odubajo was again the creator, breaking away down the right and delivering the ball across, Dallas moved on to it and smashed it past Butland from the edge of the area to give The Bees the lead.
Mascarell fired a free kick in to a defensive wall before hacking at Judge as he was looking to break away.
But that only killed the last few remaining seconds and Brentford had the win.
Brentford: Button; Odubajo, Dean, Craig, Bidwell; Douglas, Diagouraga; Jota (sub Pritchard 66 mins), Toral (sub Dallas 65 mins), Judge; Gray (sub Proschwitz 75 mins)
Subs (not used): Bonham, Tarkowski, Saunders, Smith
Bookings: Proschwitz (90 mins), Douglas (90 mins) (fourth of season), Judge (90 mins) (third of season)
Derby County: Butland; Christie, Buxton, Keogh, Forsyth; Hendrick, Bryson (sub Hughes 58 mins), Mascarell; Russell (sub Coutts 78 mins), Martin, Dawkins (sub Ibe 63 mins)
Subs (not used): Roos, Eustace, Best, Shotton
Bookings: Buxton (53 mins), Dawkins (60 mins), Martin (83 mins), Mascarell (90 mins)
Attendance: 10,608 (1,705 away fans)
By Chris Wickham