Sadio Mane hit the post and as the ball came back into the area it fell to Mohamed Salah.
His shot was cleared by John Stones straight into Ederson as the ball looped back and appeared to end up over the line to the naked eye.
But the goal-line technology used by the Premier League ruled it was not a goal.
However there is a reason the decision could have been wrong and that’s because they system used in the top flight has a 3.6mm margin of error.
The ball looked agonisingly close to crossing the line and could have been within that margin.
In the end referee Anthony Taylor ruled that it was no goal though.
And it was later confirmed the system measured the ball to be 11mm away from crossing the line.
And Liverpool ended up falling behind before half-time thanks to a left-footed effort from Sergio Aguero powered past Alisson.
Reds fans were quick to blame goal-line technology as well on social media.
One said: “To me it’s goal . City turned off goal line technology.”
Another added: “Petition to change goal line technology operating system.”
And a third said: “Goal line technology is just a scam #lfc.”
A win for City will cut the gap at the top of the table to four points.
And that will leave us with an enthralling title race in the second half of the season.
After the match tonight both teams turn their attention to the FA Cup.