Jan Holldack's stunning late strike wasn't enough to extend Brentford Development Squad's unbeaten run to eight matches as they lost 3-2 at home to Sheffield United in a bad-tempered affair at Jersey Road.
Kevin O'Connor's side found themselves 2-0 behind inside the opening 20 minutes as Jake Wright converted from the spot after he had been fouled and then CJ Hamilton made it two seven minutes later.
Courtney Senior halved the arrears before the break but The Bees cause wasn't helped when Josh Laurent was shown a straight red for an alleged stamp early on in the second-half.
Wright added his second, and The Blades third, midway through the second-half and despite some late Brentford pressure, capped off when Holldack found the top corner from 25 yards, Chris Morgan's side held on for the points.
Brentford went into the game on the back of a five match winning streak and had dumped Category One side Reading out of the Under-21 Premier League Cup last Friday but they looked far from that same side in the opening stages.
Sheffield United dominated the opening exchanges and had already seen a goal disallowed for offside before taking the lead as Wright went over in the box under pressure from Mepham. Although contact looked minimal the referee pointed to the spot and Wright stepped up to smash home past Jack Bonham.
Connor Dimaio volleyed over from the edge of the box while at the other end Senior passed up a presentable chance when he shot straight at Aaron Ramsdale after good work by Laurent.
The visitors, who themselves had won three of their last four matches, were then gifted a second goal as Wright picked up Gradi Milenge's weak backpass and squared for Hamilton to roll home from close range.
That second goal seemed to kick The Bees into life and they began to pose questions to the rigid United back four: Zain Westbrooke teed himself up to volley over the bar before playing a key role in Senior's goal. It was his run and slide-rule pass, after good hold up by Udumaga, that released the speedy winger to clip home past the on-rushing Ramsdale.
Bonham dealt well with an awkwardly bouncing Ben Whiteman free-kick and Wright sent a flick header just wide as both sides continued to create chances.
The Bees should have been level eight minutes before the break only for Ramsdale to somehow turn Udumaga's effort behind for a corner after excellent work in the build-up by Holldack.
Hamilton headed wide from eight yards and Wright slid a shot across the face of Bonham's goal for The Blades before Ramsdale ensure Chris Morgan's side went in ahead when he saved well from Udumaga.
Trailing at the break Brentford had targeted a fast start to the second-half but their plans were undone just five minutes after the break as Laurent and Wright tangled on the half-way line with referee Thomas Bishop deciding The Bees' defender had stamped on the United striker: it appeared to be a harsh decision but not out of keeping with a game that saw United awarded more than their fair share of the 50/50 decisions.
United used their subsequent extra man advantage to full effect making The Bees chase the ball for long spells and not allowing O'Connor's side a chance to get back into the game.
Morgan's men then looked to have settled matters midway through the half as Wright met an outswinging corner perfectly and powered his header into the top corner from 12 yards.
The Bees has come from 3-0 down to beat Watford 4-3 last Monday but a repeat of that looked highly unlikely as United continued to create heading into the final 10 minutes. The lively Hamilton blasted over the bar twice in quick succession after he had done well to create space for himself but The Bees did grab a goal out of nothing in injury time: Holldack was given an age on the edge of the box to pick his spot and he arrowed his effort high past Ramsdale's outstretched arm and into the back of the net.
United jitters were evident as they pleaded with the referee for full-time but there was still enough time for The Bees to threaten an equaliser. The Blades defence just about managed to clear their lines and then The Blades should have made absolutely sure of the three points on the break but Bonham was out quickly to block save from Phillips seconds before Mr Bishop blew for full-time to end The Bees five match winning run.
Brentford: Jack Bonham; Chris Mepham, Josh Laurent, Gradi Milenge, Tom Field; James Ferry, Zain Westbrooke (sub Bradley Clayton 33 mins), Jan Holldack; Herson Rodrigues Alves (sub Montell Moore 75 mins), Courtney Senior; Jermaine Udumaga Subs not used: Cameron Greaves, Zach Birse, Mergim Qarri
Sheffield United: Aaron Ramsdale; Jamie Cobain, Julian Banton, Ben Whiteman, Jake Phillips; Joel Coustrain, Connor Dimaio, David Brooks (sub Callum Semple 90 mins), CJ Hamilton; Jake Wright (sub Harvey Gilmour 85 mins), Kler Heh (sub Brodie Litchfield 77 mins) Subs not used: Joshua Perryman, Joseph Cummings