José Mourinho has admitted some Manchester United players have taken longer to emerge from their comfort zone than he expected when he was appointed manager.

When he took over last summer the Portuguese said United had to aim to become champions this season. His side is now sixth, 14 points behind Chelsea with 15 matches remaining, so that possibility appears remote.

However, Mourinho said he wanted to change the mentality of his squad and force some of them to move away from a culture where they were not expected to win every match. Although he did not name Louis van Gaal, Mourinho implied this was the culture allowed by his predecessor.

He said: “I told you in the first press conference, or second, that I was speaking about being champions because I don’t think there is another position a manager can have at this club. It would be easy for me to say we want to play better, we want to improve the quality of the game, we want to improve the relationship between the players and the fans.”

In spite of this not all of his squad responded quickly. “I didn’t know the players very well,” Mourinho said. “I didn’t know that some players need time to live with this, because it must be part of your natural habitat. Play to win, responsibility to win, cope with the pressure to win. This is something that has to belong to your natural habitat. For some guys it doesn’t. They also need that time to go out of their comfort zone or a zone where they are protected that we assume the objective is not to win – that also takes time.”

Mourinho has discussed this with Ed Woodward, the executive vice-chairman, and United’s proprietors. “Mr Woodward and the owners, we spoke a couple of times. We don’t need to speak every day because we know exactly the way to do it. I think a very good way to do it is to fight for the competitions we are in, because this helps, to play a final [in the EFL Cup], to go to the knockout stages of the Europa League again with some responsibilities, because we feel we also have responsibilities in the competition. These are all details that are going to help the people.”

During the week Rio Ferdinand, a former United defender, criticised Paul Pogba and Jesse Lingard for posting a film online of their new goal celebration. Ferdinand was unhappy that United were only sixth. But Mourinho said: “I respect Rio. He was a big guy in my club. He was a legend in my club. I am not, so as somebody that is not his level in the club I don’t think I have any legitimacy to comment on Rio. I’m not saying to you that I agree or I disagree. I’m not saying that. I’m just saying that in relation to all these people that they are, in the history of Manchester United, much bigger than I am. I don’t comment to say I agree or disagree.”

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Mourinho also brushed away how the former manager Sir Alex Ferguson was a close monitor of players’ activity on social media. “Alfredo Di Stéfano was an amazing football player but that was 30 years ago. I’m not going to compare Di Stefano with my strikers.

“Sir Alex’s time as a manager finished three or four years ago and in three or four years a lot has changed in the football world, a lot changed in society and a lot changed in the relationship between clubs and managers with the players and their entourages. It’s not good to compare moments in football. Something that in football doesn’t change, especially in my mentality, is the desire to win, the responsibility to win, the feeling that I’m never happy with myself, I always want more from myself. That is something that for me, never changes. I started as Sir Bobby Robson’s assistant in 1991, 1992. In all this period, football has changed so much. The only thing that hasn’t changed in me is that desire to work and that desire to win. I don’t accept anything that is good. You don’t want good, you want very good. That is something I always fight for every day for the people that surround me, players, assistants, medical department, everybody that surrounds me day by day. That’s something I fight and I will fight for forever. Other details related to the evolution for good and for bad, in society, it’s not possible to compare.”

Mourinho confirmed that Phil Jones will miss Sunday’s trip to Leicester City due to a foot injury.