Early bird City into

who spent almost the entire game defending, got a consolation near the end – Andre Gray tapping home Andre Carrillo’s cross.

The victory re-established City’s 15-point lead at the top – where they have been since that thrashing at Vicarage Road back in September.

But it continued Watford’s worrying tail-spin. It is six defeats now in their last seven games and after spending the first half of the season mostly in the top half of the table, they are casting anxious glances over their shoulders.

It was so easy that Guardiola was able to remove the returning John Stones and Kevin De Bruyne out of the action early.

There was triple good news for City before kick-off with De Bruyne persuading Guardiola he was fit to play despite his heavy knock at Selhurst Park, David Silva returning from compassionate leave in Spain where his wife has had complications during pregnancy and Stones appearing for the first time in six weeks following a torn hamstring.

City had averaged more than three goals a game in their last seven meetings with Watford, so it was little wonder they came out sensing an easy kill.

Even so, no one expected the Hornets to capitulate quite so early with the first goal coming after 38 seconds – the fastest goal in the Premier League this season and City’s third-fastest in the Premier League era. It was so quick that some of the hospitality guests were not even in their seats as Sterling netted his 18th of a remarkable season.

Silva sent Leroy Sane away down the left and he skinned Daryl Janmaat before delivering a first-time cross that Marvin Zeegelaar failed to cut out and Sterling converted at the far post – the sort of goal he has made his trademark.

It should have been two when the elusive Sane left Molla Wague with twisted blood and put a chance on a plate for Stones, who could be excused some rustiness after his lay-off as he skied the ball over.

But City did not have long to wait for their second and again Silva was involved. He threaded a superbly weighted pass inside Zeegelaar for De Bruyne to deliver a low cross that Kabasele turned into his own net.

If it was any consolation to the Watford defender, Aguero probably would have scored anyway had he not intervened.

It could have been a whole lot worse for the Hornets, who were being tormented by Sane’s pace.

De Bruyne clipped the bar with a free-kick, another low cross from Sane deserved to be finished off but none of his team-