Pep Guardiola has backed the PFA's threat to sue FIFA over a congested calendar that they claim is risking the welfare of stars.
Players' union chief Maheta Molango revealed his members are reaching the point of looking into legal action, after plans for expanded club and international competitions left windows for rest even narrower than they are now.
Guardiola suggested earlier this season that players should contemplate striking to show their dissatisfaction and was outspoken during the recent Club World Cup.
And the Manchester City boss reiterated his opposition to the gruelling fixture list after the champions — who will be severely impacted by the increase in Champions League and Club World Cup games — beat Sheffield United 2-0.