Manchester United boss Erik ten Hag admits their attitude wasn't good enough after defeat at Newcastle.
The visitors were second best throughout Sunday's contest as Joe Willock and Callum Wilson struck the goals for Newcastle.
Ten Hag said, "I think it was deserving for Newcastle. They were more determined and had more passion and desire to score a goal. Also, to defend their box, which they did very well. We had the spaces and the opportunities but we did not use them.
"David [de Gea] made one great save. They had many shots from the edge and we put in blocks there. But we have to stop them before they come in to the final third. We didn't do that well. The blocks were good but better is to stop it at source.
"No [the Cup runs are not affecting league form]. Always I can see the need to find stories. You have to see that every game is important, every league is important. We know how tough it is to come here and I know they want to take revenge. You have to show the same passion, desire and determination of the opponent. We didn't and we got killed.
"I am sure [there will be a reaction]. That is what we have shown all season so far."
