Jose Mourinho admits some of his Manchester United players are failing to cope with the pressure.
The Red Devils slumped to a third straight defeat in all competitions with a disappointing 3-1 defeat to Watford at Vicarage Road on Sunday.
Mourinho was asked of some his side's bigger name players, such as Paul Pogba and Wayne Rooney, and felt that perhaps they were not dealing with the pressure of playing in the Premier League and the Europa League as they probably should.
"I feel that some individuals probably feel the pressure and responsibility too much," he said.
"But from a collective point of view, I only have good things to say about them. At 1-1 everyone thinks we are going to win the game. We were showing complete control, intensity, creation.
"But their second goal is a mistake that goes against our plan and our training, because our intention was for their wing-backs to be pressed and not let them progress.
"And what happened was the guy gets the ball 20-25 metres away from our box and instead of being pressed, we give him the space to progress. (Nordin) Amrabat receives the ball and our left-back (Shaw) is 25 metres from him instead of five.
"But even at 25 you have to jump and go and press, but no, we wait. This is a tactical but also a mental attitude. It's something that doesn't become perfect in a couple of weeks. So we have to improve, no doubt, individually and collectively. And that's my job.
"We started the season very well with (winning) the Community Shield and three victories in a row in the Premier League, the best start that a new manager has had at Manchester United I think. But was I thinking that my team was ready, perfect, unbeatable? Not at all.
"I was completely aware that we were not perfect, with lots of players who are not end products and can make their own mistakes."
Marcus Rashford equalised for United in the 62nd minute after Etienne Capoue's first-half opener but Camilo Zuniga stepped off the bench to fire home for the Hornets before skipper Troy Deeney converted from the penalty spot in injury time after Marouane Fellaini had felled Zuniga in the area.