Pep Guardiola's side moved clear of closest challengers Liverpool with victory over Bournemouth at the weekend, only for the Reds to close the gap back to two in dramatic fashion against Everton a day later.
City once again play a day before the chasing pack in the midweek round of fixtures, though, and are looking to make it seven Premier League wins on the bounce.
Here, Sports Mole looks at how the champions could line up at Vicarage Road.
Sergio Aguero missed the weekend win over Bournemouth after picking up a muscular injury during training, and Guardiola admitted that he does not know whether the Argentine will recover in time for this match.
City are unlikely to take any risks over his fitness with Chelsea waiting at the weekend, though, so Gabriel Jesus is expected to lead the line once again in midweek.
Guardiola is expected to make regular changes to his side during a busy December so predicting his XI is a difficult task, but a number of the players who missed out against Bournemouth could come back into the side.
Oleksandr Zinchenko was forced off against the Cherries with what looked like a broken nose, meaning that Fabian Delph is expected to start at Watford, while the likes of John Stones, Kyle Walker and David Silva will also be hoping for a recall.