UEFA has opened disciplinary proceedings against Celtic after a fan invaded the field and tried to kick Paris Saint-Germain striker Kylian Mbappe in Tuesday's Champions League match.
In the first half of PSG's 5-0 victory at Celtic Park, the spectator ran on and swung a leg at the 18-year-old, but only hit fresh air.
The fan was caught and escorted off the field by security, and police confirmed he had been arrested.
Celtic themselves are in trouble, though, as European football's governing body has charged the Glasgow side with a violation of the disciplinary regulations.
Manager Brendan Rodgers condemned the pitch invader's actions after the match.
He said: "That reaction [jeers from the Celtic fans] said it all really. It's disappointing for any ground, any club, a supporter getting on to the pitch like that.
"It was bitterly disappointing and I'm sure the club will deal with that. Whoever that person was it shouldn't be anything we see, especially on a football field.
"I think the stewards dealt with it at the time and I'm sure the club will deal with it. The crowd and their reaction told you everything you needed to know."
Celtic have been at the centre of no fewer than 12 disciplinary offences in the last six years, with their most recent one coming in July when a section of the club's support unfurled an "illicit banner" in a Champions League qualifier with Northern Ireland's Linfield.
The club will learn the extent of their sanctions after the case is dealt with by the UEFA Control, Ethics and Disciplinary Body on October 19.
A fine is the most likely outcome facing Rodgers' side, according to precedent. Last season, Arsenal had to pay up €5,000 when a supporter invaded the field during their match against Bayern Munich at the Emirates Stadium.