Manchester City boss Mark Hughes has hinted at problems with the attitude of some players in training.
He said: "As a club we are nowhere near where we need to be in terms of preparation for games and the way players prepare on a daily basis.
"We're addressing those issues. Some players will embrace that, some won't. Change is difficult for some people and not for others. That is human nature - not football.
"You need to have mental strength and a toughness - all the soundbites people use ring true for us as professional footballers. At a top-level, high-profile club, those are the qualities you have to show on a regular basis. You can't play well for one week and then have two weeks off."