Pep Guardiola looks likely to resume rivalries with Jose Mourinho shorn of his top attacker after the Football Association (FA) charged Sergio Aguero with violent conduct for elbowing Winston Reid.
Manchester City striker Aguero has been punished for catching Reid with his arm in Sunday's 3-1 win over West Ham at the Etihad Stadium.
Referee Andre Marriner did not include the incident in his match report, with retrospective action set to be taken against the Argentina star, who could now sit out September 10's derby against Manchester United as a result.
A possible three-match ban would also rule Aguero out of subsequent fixtures with Bournemouth and Swansea City, in the EFL Cup.
An FA statement read: "Sergio Aguero has been charged for an alleged act of violent conduct which was not seen by the match officials but caught on video.
"The Manchester City forward was involved in an incident with West Ham United's Winston Reid in the 76th minute of the game on Sunday [28 August 2016].
"He [Aguero] has until 6pm on Wednesday 31 August to reply.
"Off the ball incidents which are not seen at the time by the match officials are referred to a panel of three former elite match officials.
"Each panel member will review the video footage independently of one another to determine whether they consider it a sending-off offence.
"For retrospective action to be taken, and an FA charge to follow, the decision of the panel must be unanimous."