It seemed straightforward enough. City, who went four points clear of Jurgen Klopp’s side with this win, and their fans had begun to grow frustrated at the stalemate developing in front of them when Sergio Aguero ran on to a through ball in the first minute of the second half and miscontrolled it. It rolled to Sterling, who was in an offside position.
Raheem challenged for the ball but, before he could touch it, Watford defender Daryl Janmaat tried to clear it and it rebounded off Sterling and looped over Foster into the net. The linesman on the far side flagged for offside. It looked like the correct decision even though Sterling mouthed ‘no way, no way’ as he realised the flag was up.
The laws of the game state that a player is active if he is challenging for the ball, which Sterling was. But the offside law has become stuck in confusion. The awarding of a penalty to Harry Kane in the North London derby recently, when he appeared offside, provoked a discussion with no clear outcome.
And now, with so much on the line, there was more uncertainty. For some reason, referee Paul Tierney ran over to his assistant to discuss his decision. The two men talked for three minutes, trying to keep worried Watford players at bay.
Eventually, Mr. Tierney decided the goal should stand. He pointed to the centre circle and launched a thousand more unwanted and unneeded conspiracy theories.
City would probably have won the game anyway. They were the dominant side. Watford, who had made seven changes from their last match, were offering very little.
Their football has a habit of washing away bad headlines but they struggled to break Watford. The Hornets started with a pragmatic selection, resting Gerard Deulofeu and Troy Deeney, saving them for a day when they had more chance of winning.
Straight after kick off they set up camp on the edge of their own area like an army prepared for a long siege and City began their bombardment. However tightly a team packs it defence, City always seem to be able to find holes in it and it only took three minutes for Silva to float a delicious ball over their defence for Sterling to run on to. Sterling tried to hook the ball over Foster but succeeded only in diverting it into the area.
Silva went close himself a couple of minutes later, flinging himself at a cross from Riyad Mahrez, getting to it before Foster but glancing it inches wide. After that, Watford soaked up everything, rarely venturing into City’s half.
A rather dreary stalemate ensued until just before half an hour when Aguero headed wide from a driven Bernardo Silva cross when he should have scored. Pep Guardiola turned away and held his head in his hands.
The first murmurs of restlessness began to creep into the atmosphere as half-time approached and still Watford would not yield.
City have been content to watch as the narrative unfolded that Liverpool were buckling under the title pressure. The prospect of dropping points at home to Watford had not been factored into the equation.
When the half-time whistle went, it was met with a crescendo of groans and boos. Some of them were aimed at Tierney, who had failed to spot a deflection that should have led to a City corner late in the half.
Some of them were just a response a frustrating half low on excitement and low on opportunity. Watford had not mustered a single shot, on or off target.
City had gone in goalless at the interval in their previous two league matches, against Bournemouth and West Ham, and won both games.
They are no strangers to the exercise of patience but it turned out they did not need much once the second half had begun. It was less than a minute old when Sterling put them ahead with the controversial goal.
The protests of the Watford players had barely subsided when City went further ahead. There were no arguments about the goal this time. It was fashioned by the magician David Silva, who slipped a pass through a defender’s legs and into the path of Mahrez.
Mahrez slid the ball across goal and Sterling, who was definitely onside this time, tapped it in.
Just before an hour had gone Sterling scored his third goal in 13 minutes, collecting another clever through ball from David Silva, jinking past two defenders in the box and lifting his shot over Foster who had begun to dive to his left to try to anticipate his intentions.
There was no controversy about the hat-trick goal, just brilliance from Sterling.
Watford pulled a goal back midway through the half when a long clearance by Foster was nodded on by second-half sub Deeney and allowed to run across goal by Nicolas Otamendi.
Otamendi failed to see Deulofeu, another fresh introduction, on his blind side and Deulofeu poked the ball past Ederson. It was his first touch. He had been on the pitch for 17 seconds.
Watford improved after that but they could not get the next goal they needed to put City under pressure. Before the match petered out the inquest into Sterling’s goal was already in full flow.