Ruben Amorim's side, which featured Manchester United's youngest-ever Premier League starting XI, took an early lead through Mason Mount.

However, the youthful exuberance could not prevent a Brentford comeback, as the hosts quickly asserted dominance.

Brentford responded strongly with a brace from Kevin Schade and a composed finish from Yoane Wissa, taking a 2-1 lead into the break.

An unfortunate own goal by Luke Shaw further extended Brentford's advantage early in the second half, leaving United with a mountain to climb.

Late in the game, United mounted a spirited comeback with Alejandro Garnacho and Amad both finding the net, but it was too little, too late for Amorim's men, who ultimately left empty-handed.

"I think it's a little bit of a reflection of our season. We start quite well, controlling the game, not creating big chances, but controlling the pace of the game," Amorim said, as quoted by the official Manchester United website.

"We suffer a lot with the throw-ins and set pieces, but we already knew that our team would struggle against this team because we didn't have the height [that] will be necessary for this kind of game.

"They score twice in these kind of moments, even with Matta [Matthijs de Ligt] on the floor. And then in the second half, I felt that we were near the draw, and then we suffered a goal and, like some other times, we disconnect.

"And then another goal a few minutes later. And then we push forward, try to score, we scored twice, but we didn't have the time to do better."

Asked about the importance of learning from the defeat, he added: "It's really important. They have to understand in this season, this season is really important, and also to understand that we cannot do this anymore. Of course, we know the context, but this kind of season, we need to change that.

"They need to understand what it is to play for Manchester United. I think they did really well. They are not playing so much, but then they have to play 90 minutes because we have to change some other players to save them for Thursday.

"And I think we can help even more the young kids, especially Tyler [Fredricson]. He did quite well but for the third goal he needs more help from Amad. So, with these small things I think we can help them more, but I'm really happy with the performance of the young kids."

Kaizer Chiefs coach Nasreddine Nabi bemoans dropped Soweto derby points