Manchester United manager Jose Mourinho says he knew he had a task on his hands to eradicate his team's defensive mistakes, stressing that there is no instant fix.
Mourinho went down to his third consecutive defeat in just over a week when Watford scored twice in the final seven minutes to seal a 3-1 Premier League win over United at Vicarage Road on Sunday.
The former Chelsea boss was critical of referee Michael Oliver for not awarding a foul on Anthony Martial prior to the first goal from Etienne Capoue, but acknowledged his team were to blame for the decisive second, netted by substitute Juan Zuniga 53 seconds after coming on.
Mourinho felt his defence were far too slow to close down Nordin Amrabat in the build-up and the error - for which he highlighted Luke Shaw's involvement - reminded him of Kevin De Bruyne's goal in Manchester City's derby victory at Old Trafford last weekend.
The United boss told reporters: "The only factor in my hands is the improvement of the team and individuals, trying to stop with the defensive mistakes. I knew that I had a task.
"I knew that because the first Man City goal and this second goal you can find an incredible similarity - which is [Aleksandar] Kolarov has the ball in a difficult situation in the corner and my players instead of 'go up and press' they decide to give space.
"Their second goal is a mistake. It's 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.
"I think it is Amrabat on the right side, he receives the ball, our left-back is 25 metres from him instead of being five.
"But even at 25 then you have to jump and go and press, but no, we wait. This is a tactical thing but is also a mental attitude and it's something that you don't go there and make everything become perfect in a couple of weeks.
"We gave him the space to progress, then the one against one is inside the box and when it is in the box you are not confident enough to tackle. The second goal comes from there - completely against the normal tendency of the game.
"So no doubt we have to improve individually and collectively. That's my job because lady luck and referees' mistakes you don't control - I can't do nothing [to stop them]."
However, one area that has impressed Mourinho across the three defeats has been United's battling second-half qualities.
He added: "Negative moments will always be arriving sooner or later. I feel that some individuals probably feel that pressure and responsibility too much, but from the collective point of view, I only have good things to say about them.
"If you analyse our three defeats in the last week, we were always the best team in the second half.
"We were losing against City in a difficult situation - in the second half we were strong and we deserved more. Against Feyenoord in the second half we were the only team that wants to win and then we lose.
"Today was exactly the same, we didn't start well but then in the second half they show quality, intensity, desire, commitment, ambition - all these factors - and we lose again in our best moment."