Manchester United manager Jose Mourinho was unhappy with Luke Shaw in his side's 3-1 loss to Watford in the Premier League on Sunday.
The loss was a third in a row in all competitions for Mourinho's United after they were beaten 2-1 by rivals City and then lost 1-0 to Feyenoord in the Europa League on Thursday.
Mourinho said: "The first Man City goal and this second goal against Watford -- 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 going up to press they decide to give space.
"And here for the second goal, [Nordin] Amrabat receives the ball and our left-back is 25 metres from him instead of five metres. But even at 25 metres, 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.
"I can split these defeats into three factors -- one, the referee's crucial mistakes are not in my control, there is nothing I can do about that.
"But against Man City you know what happened in minute 55 [City goalkeeper Claudio Bravo's challenge on Wayne Rooney]. You know that happened for the fist goal here and against Feyenoord there was the offside goal.
"Secondly there is [being] lucky and unlucky. It's part of the game.
"The third thing is what is my hands, which is the improvement of the team and the individuals. Try to stop with the defensive mistakes. I knew that I had a task.
"So we have to improve, no doubt, individually and collectively. And that's my job. Lady luck you don't control and referees mistakes you don't control."
United are next in action at Northampton Town on Wednesday in the EFL Cup before hosting Premier League champions Leicester City on Saturday.