Ten Hag said afterwards: "I thought we were good in certain situations and when we were winning, we didn't deserve it, but we should take the winning and do so more often.
"We were fighting and we created some great chances and Andre Onana was fantastic tonight. Rasmus Hojlund had a great chance. When you make the winning goal that is when you must bring it over the line.
"I am very pleased for Mason (Mount) but I also feel sorry for him as it should have been the winner."
The Dutchman also said: "Don't lower the performances from Brentford because I have seen them against Man City and City were also lucky to win that game. I have seen them against Liverpool and in the first 35 minutes Brentford should have taken the lead. We should have done this better. I'm not happy with the performance, it's no misunderstanding.
"The players are also disappointed by the performance but we should be consistent in the way we take a game, we (need to) go in a game and perform and show more aggressiveness especially."