Brian Quinn, the Celtic chairman, has urged Uefa to investigate the behaviour of Dida, the AC Milan goalkeeper, after the Brazilian appeared to exaggerate an injury following a clash with a fan.

The supporter ran onto the pitch following Celtic's late winner against the European champions during the Champions League group D match last night and appeared to touch Dida on the shoulder as he ran across the six-yard box.

Dida initially gave chase before falling to the floor, and was carried off on a stretcher holding an ice pack to his face.

Quinn was quick to condemn the "disgraceful" behaviour of the fan who had invaded the pitch, but felt Dida was guilty of making the most of "minimal" contact.

"I'm making no excuses for the behaviour, and the fan behaved disgracefully, but the contact made with the goalkeeper was minimal, absolutely minimal," Quinn said. "The antics of the goalkeeper have to be taken into account as well.

"All I saw were the TV pictures. He took a couple of steps after the fan and then obviously made this decision that he should go to ground. Unless I missed something he was carried off on a stretcher for what seemed to be the lightest tap you can imagine."

Quinn confirmed his club would investigate how the fan had been able to run onto the pitch and would seek to take the "appropriate action" against the individual concerned.

Asked if he had tried to see Dida after the game, Quinn said: "I didn't, certainly not. It's not my place to go into the opposing dressing room. We spoke to the officials of Milan, they were not ranting and raving, they were being sensible."

William Gaillard, the Uefa communications director, said that the European governing body expected to receive their match delegate's report by the end of this week. "One of our prosecutors will look at the document and decide whether to open an investigation," Gaillard said. "If he opens an investigation it will be a week or two before the disciplinary body deals with the case.

"I don't want to presume anything. There is a whole range of possible punishment but of course there are precedents for the same kind of incidents."

Scott McDonald, the Celtic striker, has urged Uefa to be lenient on the club. It was the Australian's late winning goal that sparked the incident. "I hope the authorities are lenient," he said. "The big man [Dida] has been hit by all sorts of things in the past and I don't know how hard he was hit.

"He's been hit by a flare before, so he's been through the works. I didn't see what happened, I was too busy celebrating, but Dida has gone down as if he's been shot.

"It would be a tragedy if what happened affected the team. It's a career highlight for me to get the winning goal against the European champions. It's a fantastic feeling and something I'll hold for the rest of my life."

In 1984, Celtic were ordered to replay a Uefa Cup tie against Rapid Vienna - which they lost at Old Trafford - after a player was allegedly hit by a bottle.

Two seasons ago, Inter Milan were forced to play four games behind closed doors and were fined after a flare hit Dida during a Champions League quarter-final between the city rivals at the San Siro. The tie was awarded 5-0 to AC Milan.

More recently, Denmark were ordered to play four home European Championship qualifying matches at least 250 kilometres away from Copenhagen and fined £41,000 after a fan invaded the pitch and assaulted referee Herbert Fandel during a match against Sweden in the Danish capital in June. The match was awarded 3-0 to the Swedes, although Uefa did subsequently agree to slightly relax the restrictions on where future games could be played.