Brentford manager Thomas Frank was annoyed with a "stupid" penalty in the 3-0 loss to Manchester United on Monday night.

Rico Henry fouled Cristiano Ronaldo in the box and the Portuguese duly stepped up to put United ahead by two goals.

"Second half I saw much more of my team and the way we want to play," he said.

"I think we were more aggressive, more on the front foot, I think we were better on the ball and were absolutely in the game.

"And then we gave away a stupid penalty. I think it's not necessary to make that one and to make a mistake there.

"Then of course that took a little bit of air out of everything and we concede on a set-piece.

"A better second half but we concede two goals in the second half that we should never concede if we want to get a result here.

"I'm just disappointed because I felt that there was an opportunity here tonight but United performed well and if we're not at our level then it's difficult."