It was shortly after Edinson Cavani struck a penalty past Craig Gordon on Tuesday evening when a Celtic fan ran onto the pitch.
PSG had just gone ahead 3-0 against Celtic, well on their way to inflicting the worst ever home European defeat the Scottish club has suffered.
In a moment which encapsulated Celtic's evening, the fan swung a leg at Kylian Mbappe and missed. As he did so - and after - he was widely booed by the Parkhead crowd.
Footage of the incident has since emerged via Twitter user Paul Rouget.
The fan - a 21-year-old from Belfast - was, on Wednesday, banned from every football ground in the UK by a Glasgow court.
UEFA have opened disciplinary proceedings against Celtic. It will be next month before they discover the punishment.
La tentative d'agression sur Kylian Mbappé filmé depuis les tribunes du Celtic Park #Celtic #PSG pic.twitter.com/BBlJR3Av4v
— Paul Rouget (@PLRGT) September 14, 2017
