Yaya Toure has been told by Pep Guardiola he will not play again for Manchester City until his agent apologises for speaking out in the media.
Toure's representative, Dimitri Seluk, recently suggested manager Guardiola humiliated the midfielder by leaving him out of City's Champions League squad.
The Ivorian has appeared in just one of City's eight games this season - not even making the bench for the other seven - and it was assumed this was because he did not feature in Guardiola's plans.
But now Guardiola has revealed there is more to it, with the Spaniard angered by Seluk's frequent comments to the press.
Guardiola said: "It was so difficult for me to put him out of the Champions League, so difficult. I know him, I know he's a good, good guy, but the list is the list.
"But the day after his manager spoke, in that moment Yaya is out. I accept if Mr Dimitri Seluk came in a press conference or (spoke to) his friends in the media - because he has not the courage to call me - and apologised to Manchester City, his team-mates and the trainer, when that happens Yaya will be part of the group and he will have the same chance to play all the games.
"I cannot accept as a coach, every manager when his player doesn't play, going to the media to speak and speak and speak.
"I know how Dimitri Seluk loves Yaya Toure. If he loves me, show me and make apologies to Manchester City what he did with the journalists."
Seluk has a long history of controversial remarks concerning his client, most notoriously in 2014 when he claimed the club showed him a lack of respect on his 31st birthday, not even giving him a cake.
Now it seems Guardiola, who previously coached Toure at Barcelona, is not prepared to accept any interference in squad matters from intermediaries.
Guardiola said: "I cannot imagine in my period when I was a football player, my manager going to the media and speaking against Johan Cruyff, about this and about that.
"Maybe it's a new era now, the new period changing, but I'm an old guy. I am old generation, and (an) old generation manager has to make his players his job and trainers his job.
"Today the managers (agents) believe they are more than they are. If he has a problem call (director of football) Txiki Begiristain, the club, and they can talk. Until he doesn't speak, Yaya is not going to play."
Guardiola was speaking at a press conference to preview Wednesday's EFL Cup tie at Swansea.
It was a game Toure, 33, was expected to come back into the reckoning for but Guardiola immediately ruled the player out when asked.
"He is not in the team," Guardiola said firmly. He was asked for clarification of the situation because it was reported last week that Toure had missed training with a migraine.
"Yaya was four days off with a headache, he was not here," Guardiola confirmed before adding he was now back in training.
Guardiola's revelations came on the same day Toure, of the Ivory Coast, announced his retirement from international football.
Toure wrote in a statement: "The fact that I am 33 now, the intensity of training and the multitude of games are not the reasons why I am making this decision.
"Football is everything to me and it gave me so much in my career that I no longer feel able to set myself new goals as a player with the Elephants of Ivory Coast. I would like to say solemnly that I am stopping!"