A fan ran on to the pitch and appeared to aim a kick at Paris St-Germain’s Kylian Mbappe during the French club’s Champions League victory at Celtic.
The incident happened during the first half of Tuesday’s match at Celtic Park, shortly after the visitors’ third goal.
As the host team, the Scottish champions could face action from tournament organisers Uefa.
PSG went on to win the match 5-0, making it Celtic’s heaviest-ever home European defeat.
Celtic manager Brendan Rodgers said he was pleased the rest of the sell-out crowd booed the intruder.
“I think their reaction said it all,” he said. “It was disappointing at any ground, at any club, a supporter getting on the pitch like that.
“It was bitterly disappointing and I am sure the club will deal with whoever that supporter was. It shouldn’t be anything that we should see.
“I think the stewards dealt with it at the time and I am sure the club will deal with it.”
In July, Celtic were fined £20,600 after an “illicit banner” was displayed during their qualifying win over Linfield.
It was the club’s 11th punishment in six years relating to misconduct from supporters during European ties.
Following the initial charge, they announced a two-game closure of the area of the stadium occupied by the Green Brigade fans’ group.