Manchester City destroyed Shakhtar Donetsk 6-0 at the Etihad Stadium on Wednesday night.
First half goals from David Silva and Gabriel Jesus gave Manchester City a 2-0 lead going into half-time.
And Pep Guardiola's side would score four more times after the break.
Gabriel Jesus managed to hit the back of the net twice more to complete his hat-trick, while Raheem Sterling and Riyad Mahrez also found themselves on the score-sheet.
Man City consolidated their lead in Group F and they are now all but ensured of a spot in the last 16 of the Champions League.
The home side were given two penalties on the night, both of which were converted by Jesus.
But it is the first one of those that has been the major talking point.
Raheem Sterling appeared to kick the turf when attempting an effort on goal.
Despite being nowhere near a Shakhtar player, the referee gave a penalty to the English side.
It has been dubbed 'the worst penalty decision of all time', and you can see why.
So, what did Pep Guardiola think of it?
Unsurprisingly, the Spanish manager admitted that it was never a penalty.
But when asked whether Sterling could have told the referee that it was not a penalty at the time, Guardiola couldn't resist bringing up Liverpool.
In their Champions League quarter-final last season, a perfectly legitimate goal from Leroy Sane was disallowed by the referee.
Sane was ruled offside, but, as replays showed, that was not the case as the final touch had come off James Milner.
Remind yourself of that goal from 2:24 below:
And it seems Guardiola still remembers that moment very clearly.
Guardiola defended Sterling's decision by saying that Milner could have informed the referee that it came off him in that game.
"Yeah he could do that," when asked if Sterling could have told the referee he had fallen down without any contact from a Shakthar player.
"But last season, Milner could have said our second goal in the 44th minute was a legal goal."
To be fair, he has a point. But is it really necessary to bring up Liverpool when asked about Sterling's penalty incident?
It does seem a bit odd.
And Liverpool fans are accusing Guardiola of being obsessed with them following his comments.