Joe Hart claims Manchester City's players have failed Manuel Pellegrini this season and been "baffled" by the slump that has left the champions battling for the top four.
City face West Ham at the Etihad Stadium tomorrow just four points clear of Liverpool after a run of four defeats in six Premier league games.
Last Sunday's derby defeat against Manchester United at Old Trafford saw Louis van Gaal's team open up a four-point gap between themselves and City, who stood joint top with Chelsea on January 1.
But with City's loss of form now becoming an issue which threatens Pellegrini's job security, goalkeeper Hart admits the players have let down the manager.
"It's been difficult, difficult moments," Hart said. "That's a team of winners and when you don't win, it's going to be difficult. We want to win, we've got high standards. People have been disappointed in their own performances.
"We've let the manager down a few times in certain games and we've baffled ourselves a little bit because we feel like we've got the quality to beat anyone and that's not been the case. He (Pellegrini) has been great. He's hard, he kind of says it how it is and you can't ask for more than that."
Pellegrini, who confirmed that captain Vincent Kompany may miss the rest of the season with a groin injury, has warned his players that a failure to rediscover their form could see them finish as far down the table eighth.
"Every time you finish the season, you must analyse, winning or losing," he said.
Man City v West Ham, live, tomorrow, Sky Sports 1, 1.30pm