The expanded UEFA calendar has complicated domestic competitions and City’s draw to face the Hornets clashed with a Europa League clash at Old Trafford.
Manchester United host FC Twente on September 25 and local police forces don’t have the capacity for both clubs in the city to play on the same day.
City have agreed to switch their Carabao Cup third round tie to the Tuesday but that does present logistical issues for Pep Guardiola.
The Premier League champions meet Arsenal at the Etihad Stadium at 4:30pm on the Sunday, offering minimal rest bite between fixtures.
City have won their opening three games this season but are set to be tested by their upcoming schedule
These problems come in the first weeks of the English authorities attempting to navigate a congested schedule by staggering Carabao games for those teams competing in Europe.
Guardiola is spending time travelling around Norway during this international break - and plans to go fishing in Lofoten - but the headache of the calendar will have dampened his time away.
UEFA’s schedule is thought to take precedence in a situation such as this, meaning United’s game couldn’t be moved to the Thursday.
The Europa League has extended its first matchday across Wednesday and Thursday but once United’s game had been set the governing body were reluctant to move it.