Manchester City's clash with West Ham was dominated by VAR, with three big calls made including the decision to controversially rule out a Gabriel Jesus goal for offside.
Raheem Sterling was adjudged to be offside in what was an extremely tight call as he raced onto David Silva's through pass before squaring for Brazilian Jesus to tap home what he thought was his side's third goal.
But the VAR advised referee Mike Dean that the goal should be disallowed, with City's celebrations short-lived as the scoreline remained at 2-0 to the visitors at the London Stadium.
Sterling's body was ruled to be in front of West Ham defender Ryan Fredericks, who was essentially directly alongside the England international.
It was certainly an extremely tight call, with the camera angle provided to make the decision hardly ideal in comprehensively ruling that Sterling was definitely ahead of Fredericks.
And City were not impressed with the decision, with the former Liverpool winger racing to ref Dean to query the call, while Jesus was also dumbfounded as he initially didn't understand why the goal had been chalked off.
The debate will rage over whether it should have been reviewed in the first place, with the purpose of VAR being to aid the referee in making decisions regarding the correction of "clear and obvious errors".
The Premier League champions had been 1-0 ahead at the interval, with Jesus steering home Kyle Walker's ball across after Issa Diop had deflected the ball into the Brazil international's path.
Pep Guardiola's side increased their lead in the second half as Sterling slotted home Kevin De Bruyne's through pass to leave Lukasz Fabianski in the West Ham goal with no chance.
Then came the first controversial VAR incident, with Jesus believing he'd scored his second of the afternoon only for the goal to be overruled.
And the VAR controversy wasn't over there, with Sterling putting City three ahead - a strike that was again checked for offside but, this time, the goal was given.
In yet more drama, Sergio Aguero was also allowed to retake a missed penalty after a number of West Ham players were deemed to have entered the penalty box prior to the Argentine striking the ball.
VAR is being introduced in the Premier League for the first time in the 2019-20 season having previously been used in other leagues across Europe, as well as the Champions League.
It has also been tested in England previously by its use in the FA Cup and Carabao Cup.