Connor Lemonhaigh-Evans hat-trick sinks Bees at FailandLee Carsley's Development Squad had no answer to a Connor Lemonhaigh-Evans hat-trick as they started the new year with defeat away at Bristol City.
The game was barely two minutes old when the City striker grabbed his first with a neat finish past Richard Lee.
Brentford levelled on 20 minutes as Jermaine Udumaga scored from the spot but parity lasted only two minutes before Lemonhaigh-Evans scored his second.
Bobby Reid made it 3-1 just before the half-hour but again Udumaga responded, this time with a low drive into the corner from outside the box.
Trailing 3-2 at half-time any hopes The Bees had of a fast start to the second-half evaporated almost instantly as Reid grabbed his second within 90 seconds of the restart and Lemonhaigh-Evans added the gloss with his third late on.
Lee's starting XI was a mixture of youth and experience with Richard Lee starting in goal behind a back-four which included Audrius Laucys and first-year scholar Seth Owens.
Raphael Calvet started in a holding midfield role with Jermaine Udumaga behind the three of Josh Clarke, Betinho and Charlie Adams.
The hosts had former Brentford defender Karleigh Osborne playing in the middle of a back three with Ben Withey and Jamie Horgan pushing forward as wing-backs.
It took City less than two minutes to take the lead as Lemonhagh-Evans got in behind The Bees backline and gave Lee no chance as he lifted the ball over him and into the back of the net.
The goal settled The Robins and they dominated the early stages of the match with Withey and Horgan getting a lot of joy pushing on from wing-back and doubling-up on The Bees fullbacks.
Gus Mafuta thrashed wide from the edge of the box and Daniel O'Shaughnessy was in just the right place to block from Lemonhaigh-Evans as the goal gaped after Lee had raced out of his box to tackle Reid.
Reid shot over from 18 yards but then, against the run of play, Udumaga levelled matters from the spot after Owens had been hauled down at a corner.
Any hope Lee Carsley had that his side would use the goal as a springboard was quickly dashed as Tom Fry, who would impress all afternoon on the left of a midfield three, broke down the right and crossed for Lemonhaigh-Evans to control and fire home from close range.
Louis Hutton then passed up a glorious chance to level things once more as he pulled his shot from 15 yards agonisingly wide of the post after Osborne's poor clearance.
That miss looked even more costly as Bristol made it 3-1 five minutes later with Fry again the architect down the right, this time it was Reid on the end of this cross to poke past Lee.
Lemonhaigh-Evans pulled wide when presented with a chance to wrap up a first-half hat-trick and then saw a shot bravely blocked by O'Shaughnessy before Osborne was denied well by Lee.
On the balance of the opening half-hour The Bees had been on the ropes but they soon reduced the arrears to just one goal.
Bristol City's wing-backs had been enjoying life going forward but they were caught out as Brentford broke four on three and Udumaga carried the ball to the edge of the box before arrowing a drive into the bottom corner.
Despite conceding three in the first-half Lee had made a number of crucial saves in the opening period and he added another to the list as he turned away Reid's close range effort.
The Bees were fortunate to be only one goal behind going in at half-time but they suffered the worst possible start to the second-half conceding a very soft fourth, 90 seconds into the half.
A Brentford corner was cleared and one long ball saw Reid win the one-on-one footrace with Greene and he turned the full-back and slid home from 10 yards.
The game had been played in terrible conditions from the outset and the heavy pitch, wind and rain meant the second-half became a more scrappy affair.
Adams saw a shot deflected over the bar and Betinho was inches away from turning Adams' delicious low cross in at the back post.
The diminutive winger came close again as David Richards showed good handling in the difficult conditions to hold his free-kick as Brentford pushed for a third to set up a grandstand finish.
However that goal failed to materialise and Lemonhaigh-Evans grabbed his third with 10 minutes to go, to put the result beyond doubt, as Shaquille Hunter slipped the ball into the striker and he swept home from 10 yards.
Hunter was denied in the dying seconds as Lee made a good low save while at the other end Udumaga should have completed his hat-trick but he shot straight at Richards from 12 yards as Brentford slipped to consecutive league defeats.
Bristol City DS: David Richards; Ben Withey, Zak Vyner, Karleigh Osborne (sub Ben Last 71 mins), Billy Murphy, Jamie Horgan; Tom Fry, Jordan Wynter, Gus Mufata; Bobby Reid (sub Shaquille Hunter 71 mins); Connor Lemonhaigh-Evans (sub Liam Monelle 85 mins)
Subs not used: Jojo Wollacott, Matthew Long
Brentford DS: Richard Lee; Audrius Laucys, Daniel O'Shaughnessy, Seth Owens, Aaron Greene; Raphael Calvet; Josh Clarke, Jermaine Udumaga, Louis Hutton (sub James Ferry 71 mins), Charlie Adams; Betinho (sub Kyjuon Marsh-Brown 65 mins)
Subs not used: Jack Warburton