Don Balon cites a high level City source, who says tension inside the locker room is growing.
City's players are upset with the micro-management of Guardiola, including "strict schedules and routines that must be fulfilled to the letter". There is also an internal code the players must adhere to.
The measures have upset the playing group, with the Spaniard's strict regime in contrast to former manager Manuel Pellegrini's more relaxed ways.
Guardiola takes City to Manchester United on Saturday for the first big test of his reign.