Mnchester United boss Erik ten Hag admitted "mixed feelings" after their 2-2 draw with Leeds United on Wednesday night.
United came from 2-0 down to earn the point.
Ten Hag said: "Mixed feelings. Of course in the end we were happy to win a point - but we dropped two points. It's a very bad start, unacceptable, especially in a derby you have to be ready to battle and take responsibility. We didn't do that."
Did the quick start surprise the players? "It looked like it but not me. [We knew] they will go aggressive, front foot, against a team on a good run they'll try to get into duels and that's what they did.
"We created great chances. Garnacho twice. Sabitzer. The header of Raphael. At half-time we had to equalise. If you start the second half the same as the first half you make it really difficult.
"I have to complement the team and resilience to fight back. We made two great team goals.
On bringing goalscorer Jadon Sancho on, he added: "I wanted a different dynamic. In that moment we weren't in the game. Luckily it succeeded because we scored two goals. Very happy. He's all the way back. We know he's a magnificent player. I think consistently he can have a big impact. But he has to work hard. It will motivate him to get more. I really enjoyed it, especially for him. It will strengthen him.
"If you play a derby you need a different attitude. You have to start and be ready and take responsibilty, win your battles and be composed on the ball."