Jon De Souza's Youth Team extended their unbeaten run in the Under-18 Professional Development League Two South to four matches after a 1-1 draw at home to Swansea City.
It was a first-half of few chances but Herson Rodrigues Alves passed up the best of them sidefooting wide from close range after Lewis Thomas had parried James Ferry's shot.
The second-half also took a bit of time to get going but when it did it was Swansea City who took the lead as Owain Jones rifled home from the edge of the box.
The Swans, who had beaten Brentford 4-1 back in December, should have put the game to bed after that as Dan James and Dylan Thomas both missed glorious chances to double the visitors lead.
Those chances were to come back to haunt Swansea as Bradley Clayton struck in the seventh minute of added time to secure the point.
Jon De Souza made one change from last Saturday's 3-2 win at Chalrton Athletic as Rodrigues Alves, who signed a new contract during the week, replaced Seika Jatta.
The Swans lined up in a 4-1-4-1 formation with the lively trio of Stephen Fallon, Owain Jones and Dan James operating in the more advanced roles.
With both sides renowned for their passing football the opening quarter of an hour saw little in the way of goalmouth action as the two teams sized each other up.
The nearest either side came to a goal saw Nik Tzanev out bravely to make a block save at the feet of Jones after a poor ball across his own box by Audrius Laucys.
Slowly however the game came to life as James was inches away from turning home Jones' cross before Reece Cole fired a clever free well wide from distance.
A flowing Brentford move involving Zain Westbrooke and Cole freed Clayton but Lewis Thomas was out smartly to save while Jordan Sherman got a vital touch to deflect Rodrigues Alves' shot over the bar.
Milenge headed wide from a corner, Audrius Laucys saw his shot blocked by a crowd of bodies before Cole fired the rebound over as Brentford started to gain the ascendancy on the way through to half-time.
That ascendancy should have been rewarded with a goal right on the stroke of the interval but Rodrigues Alves could only cushion wide with the goal at his mercy after Ferry's shot had been parried by Thomas.
Brentford continued to control without really dominating in the opening stages of the second-half with Westbrooke shooting inches wide but on the hour things changed.
The Bees began to give away possession and invited Swansea pressure onto them.
A loose free-kick on the edge of the Swansea area saw the visitors break but Seth Owens made an outstanding tackle to stop Jones' run.
If that wasn't enough of a warning them Brentford were handed an even bigger one a minute later as Aaron Lewis hit the post and then James inexplicably shot over an open goal.
However, the league leaders failed to heed those warnings and were punished in the 63rd minute as Fallon slipped in Jones and he rammed home from 18 yards.
Brentford sought an immediate leveller and Cameron Gilchrist saw yellow for cynically bringing down Rodrigues Alves inside the D - Westbrooke's free-kick hit the wall and Owens' follow-up was well turned over by Lewis.
As the game entered the final quarter of an hour The Bees threw more men forward and Swansea began to look a real threat on the break.
Tzanev didn't know much about turning over a James' effort while at the other end Clayton shot wide from 18 yards.
Jones couldn't turn home from close range as a combination of Laucys and Tzanev barred his route to goal before Thomas missed an absolute sitter to make it 2-0 as he swept wide of the post from eight yards.
Swansea's timewasting actions began to infuriate the Brentford players and supporters as the visitors' players' dropped left, right and centre needing attention.
Players from both sides began to get involved in bitty confrontations as it looked like the visitors might hold out.
Westbrooke shot over from the edge of the box but just as it looked like the three points would be going back down the M4 Clayton struck in the 97th minute.
Makhosini Khanye's cross was blocked but Tom Field's ball in found it's way to the back post where an unmarked Clayton was on hand to bundle home and spark wild scenes of celebration both on and off the pitch.
Brentford YT: Nik Tzanev; Audrius Laucys, Gradi Milenge, Seth Owens, Tom Field; James Ferry, Zain Westbrooke, Reece Cole (Makhosini Khanye 73 mins); Herson Rodrigues-Alves, Bradley Clayton, Jeremiah Kamanzi (sub Kyjuon Marsh-Brown 61 mins)
Subs not used: Tom Roberts, Tony Guppy, Romayne Pennant
Swansea City YT: Lewis Thomas; Aaron Lewis, Cameron Gilchrist, Jordan Sherman, Cai Owens; Stephen Fallon, Jamie Latham, Adnan Maric; Dylan Thomas, Daniel James; Owain Jones (sub Brandon Griffiths 90 + 3 mins)
Subs not used: Gareth Owen, Keston Davies, Ashleigh Harries, Joseph Rodon