Betinho's late goal wins derby against QPRLee Carsley's Development Squad made it back-to-back league wins with a 2-1 success over local rivals QPR at a cold and windy Jersey Road.
Playing into the teeth of the wind in the first-half The Bees found it tough going but took the lead from the spot ten minutes before the break as Jermaine Udamaga converted after Courtney Senior had been fouled.
Jack Bonham saved a penalty before half-time for The Bees but QPR did find a way back into the game six minutes into the second-half as Josh Hunt-Laurent fired home from 25 yards.
It looked like the game would end all square but Betinho grabbed the winner for Brentford in the last minute finishing calmly after good work from Marcos Tebar.
Lee made three changes from the win over Bristol City last Monday as Marcos Tebar, Betinho and Josh Clarke came into the starting eleven.
QPR started far the brighter as their high-pressing game put Brentford under pressure playing against the strong wind.
The Bees found it difficult to play their way out and anything hit slightly longer held up on the wind and came straight back towards Brentford's goal.
It was the visitors who created the only real goalscoring chances of the opening 20 minutes as Aaron Mitchell pulled a shot wide as Nico Yennaris lost the ball on the edge of the box and Hunt-Laurent should have done better when presented with the ball unmarked 12 yards out, his shot bobbling tamely wide.
Slowly as the half went on and The Bees got used to the fierce conditions they began to impose their style on the game.
With the pace and trickery of Courtney Senior and Montell Moore and the movement of Betinho pulling the Rangers' back-line around the pitch Brentford began to come into the game more.
Moore flashed a free-kick across the face of goal before he was booked for simulation as he went over on the edge of the box.
Comley was inches away from putting the ball into his own net as he diverted Moore's cross inches wide of the near post.
QPR's threat was now being contained to either Brentford errors or efforts on the counter-attack as Brandon Comley dispossessed the over-playing Tebar but his pass was too far in front of Bruno Andrade.
Jack Bonham showed good handling to hold a shot from Andrade before The Bees opened the scoring on the half-hour.
Senior burst into the box and drew a foul from Mitchell, Udamaga stepped up and fired the penalty low to the keeper's right from the spot.
Brentford should have made it two shortly afterwards but Senior delayed crossing the ball and when it did come in Darnell Furlong flew in to make an excellent block as Tebar looked to fire home from six yards.
The Bees were well on top now and could have had a second penalty before the break as Yennaris broke into the box and was clipped by Joe Lumley, the midfielder elected to stay on his feet much to his credit and his attempted cross was hooked away to safety.
Having been dominated in the latter stages of the first-period Rangers could have gone in level as Udamaga gave away a penalty for handball after a great run by Andrade but the Rangers' winger's spot kick was tame and Bonham got down to turn behind.
After that let-off Brentford really should have doubled their advantage with the last kick of the half as they broke from the corner but Josh Clarke's cross was turned wide by an unmarked Betinho on the penalty spot.
With the wind in the second-half Brentford might have been expected to dominate the match and in the early stages it looked like that would be the case.
Udamaga nearly scored his second almost directly from the kick-off but Lumley made the save and Moore pulled a shot across the face of goal after getting in behind the Rangers' backline.
However the complexion of the match changes six minutes into the second half as Hunt-Laurent cut inside from the left and arrowed an unstoppable drive past Bonham from 25 yards.
QPR, who led the table going into the match, began to look like table toppers moving the ball around well and threatening Bonham's goal.
The Brentford keeper made a fine double save from Ben Pattie and Nathan Corkery while Andrade shot over from distance after cutting inside.
Clarke could have restored Brentford's lead on the break but he sliced a shot well side from a central position inside the box.
At the other end Andrade headed wide from a corner before the visitors were convinced that Hunt-Laurent had grabbed his second as his shot, they thought, bounced off the stanchion of the goal but the referee correctly decided that it had just rebounded off the post.
After that let-off for The Bees, and as the game entered the final 20 minutes, the match became stretched with both sides searching for a winner.
Clarke saw a shot blocked by Addison Garnett and Bonham saved well from Corkery before making a great recovery block from Corkery after Andrade's shot had bounced in front of him and rebounded off the former Watford man.
Moore tested the handling of Lumley from distance before an incisive Brentford break in the final minute settled matters.
Tebar won the ball back from Pattie high up the pitch and fed Betinho who kept his cool to calmly fire past the on-rushing Lumley.
With time running out QPR threw everything at Brentford as Bonham saved from Mitchell and Pattie headed Olamide Shodipo's inviting cross wide at the back post.
The hosts could have added a third in the dying seconds as another quick counter led by Moore and Clarke freed Betinho and the Portuguese striker's exquisitive lob looked to be destined for the back of the net but Darnell Furlong scampered back to clear off the line.
In the end two goals were all Brentford needed as they secured back-to-back wins in the Under-18 Professional Development League Two South.
Brentford DS: Jack Bonham; Josh Clarke, Raphaël Calvet, Daniel O'Shaughnessy, Aaron Greene; Nico Yennaris, Marcos Tebar; Montell Moore, Jermaine Udamaga (sub Seika Jatta 82 mins), Courtney Senior (sub Kieran Morris 68 mins); Betinho
Subs not used: Mark Smith, James Ferry, Louis Hutton
QPR DS: Joe Lumley; Darnell Furlong, Addison Garnett, Harly Wise (sub Nathan Corkery 45 mins), Nico Hamatairen; Gio Critchlow (sub Olamide Shodipo 65 mins), Brandon Comley, Josh Hunt-Laurent, Bruno Andrade; Ben Pattie, Aaron Mitchell
Subs not used: Aaron Lennox