Manchester United's boss Jose Mourinho has attributed his side's 2-1 derby loss to Manchester City to a poor first-half performance.
City went 2-0 up under 40 minutes through Kevin De Bryune and Kelechi Iheanacho.
But a mistake from Claudio Bravo on his City debut was pounced on by Zlatan ibrahimovic to end the first half 2-1.
"What did I make of today? I think in the first half they were much better than us. We started the game badly," Mourinho said in his post-match reaction.
He criticised the performance of some of his players.
"We started the game with some players really below the normal level, in terms of their concentration, of their mental ability to play a game of this speed because you need to be sharp in the way you think, the way you play.
"In a match of this dimension, when you have three or four players not at that level, you pay for that. The team paid for it.
"In the first half, for 35 minutes it was City in control, City deserved to be in front. In the last period of the first half we scored a goal and we could immediately score again but I think that was outside the context of the game in the first half.
"The second half was completely different, and when they brought on Fernando, they were feeling what everybody was feeling, that we were in control. We were much more dangerous, we had our chances to equalise and who knows what could happen if we had equalised. For 45 minutes, we fought really hard. We tried everything, took lots of risks and deserved a different result."
Mourinho went on to question some of the referee's decision.
"I think we were punished by a lot of things. First thing: our first half – the way we started, some individual performances made the team look fragile. We were also punished by two decisions of Mark [Clattenburg], because even the best referees can make mistakes and he made two mistakes. The first one is Bravo [on Rooney] – it’s a penalty and a red card. If any player does that outside the box, it’s a direct free-kick and a red card, so inside the box it’s a penalty and a red card. But the referee maybe thought of the consequences of that because the consequences would be a completely different game and he didn’t want to take that decision, which would be very important. And the second one is another penalty – Otamendi, with his elbow. He tries to stop the cross that’s going in front of him but the cross goes behind him, he’s looking to the ball and brings the arm and elbow back, and it’s another clear penalty. So we were also punished by that."