After trailing 2-0 after 36 minutes in The Etihad Stadium Leicester City managed to claw themselves a lifeline by half-time through a Shinji Okazaki strike to make it 2-1.
In the 77th minute, it looked like Leicester were going to equalise when Riyad Mahrez was taken down for a penalty by Gael Clichy and the Algerian stepped up to take responsibility.
Mahrez slipped while striking but still hit the back of the net. He turned to celebrate but he was soon stopped by a protesting Willy Caballero and referee Bobby Madley.
Madley blew his whistle almost immediately and awarded a free out to City after it appeared Mahrez struck the ball twice before it went into the net.
Replays show it was indeed the correct decision, a huge moment in the race for the Champions League places.
It is not the first time this may have happened this week. Replays of Antoine Griezmann's penalty mid-week against Real Madrid showed that the French man may also have struck the ball twice but in that case the goal was given.