It should have been a fantastic night for Celtic, and in so many ways it was. Scott McDonald scored a 90th-minute winner to put Milan, the European champions, to the sword and breathe fresh life into Celtic's Champions League campaign with a famous victory. In a madcap game that had a particularly pulsating second half, Stephen McManus put the hosts ahead via a deflected corner, Milan levelled with a controversial penalty, converted by Kaka, and then McDonald, a little Australian with a big appetite for glory, stole in to send fortress Parkhead into rapture.
Yet that will not be dominating the agenda in the coming days in what has proved to be another famous week for Scottish club football. Attention will instead focus on how on earth a Celtic "fan" managed to get on the pitch – as Celtic celebrated McDonald's goal – and strike out at the face of Dida, Milan's goalkeeper. It did not look to be a powerful blow; in fact it seemed to be more of a tap. But that is not the point. Dida turned to chase the offender off the pitch and while doing so fell to the turf for reasons still to be confirmed late last night. He ended up being taken from the pitch on a stretcher.
Uefa, European football's governing body, is certain to launch an investigation this morning, primarily into how a supporter managed to attack a player. In theory, Celtic could face sanctions ranging from a fine to deduction of points. Being forced to replay the game or being thrown out of the tournament are also possible punishments.
However, Uefa might also look at Dida's behaviour and ask him, after watching evidence, what made him collapse as if poleaxed. If simulation were to become a theoretical accusation, albeit in bizarre circumstances, Milan might actually back away from seeking to have Celtic punished. Certainly their manager, Carlo Ancelotti, seemed to have no appetite last night to pursue the matter.
"I didn't see it, but it had nothing to do with the final result," he said of the incident. "We made a mistake in defence for their winning goal. It was a tight game, very physical, on a slippery pitch. Neither said had too many chances."
Asked if Milan would try to overturn the result he added: "I don't know if we'll make a case to Uefa, but I don't think so."
His counterpart, Gordon Strachan, preferred to talk about an "excellent" game, McDonald's "thoroughly deserved goal, because he's got guts" and "a wonderful couple of nights for Scottish football", following Rangers' win in Lyons on Tuesday.
He agreed with the vast majority of those present at the match, neutrals included, that Milan's penalty was something of a mystery. It was awarded after some opaque offence, probably related to Lee Naylor tussling with Massimo Ambrosini while the ball was nowhere near. "The anger was in my team's play after that [injustice] and it gave them the energy to get on with things," Strachan said.
So Celtic's formidable home record in Europe's top-table tournament goes on. In their last 19 Champions' League matches at home, qualifiers included, they have lost just once. Of more immediate relevance is they lie second in Group D with three points few people expected them to have.
Celtic (4-5-1): Boruc; Perrier-Doumbe (Kennedy, 79), Caldwell, McManus, Naylor; McGeady (Nakamura, 84), Hartley, S Brown, Donati, Jarosik (Killen, 84); McDonald. Substitutes not used: M Brown (gk), Riordan, Sno, O'Dea.
Milan (4-4-1-1): Dida (Kalac, 94); Oddo, Nesta, Bonera, Jankulovski; Gattuso, Seedorf (Gourcuff, 55), Pirlo, Ambrosini; Kaka; Inzahgi (Gilardino, 77). Substitutes not used: Emerson, Simic, Favalli, Brocchi.
Referee: M Merk (Germany).
Results: Milan 2 Benfica 1; Shakhtar Donetsk 2 Celtic 0; Benfica 0 Shakhtar Donetsk 1; Celtic 2 Milan 1.
Remaining fixtures: 24 Oct: Benfica v Celtic; Milan v Shakhtar Donetsk. 6 Nov: Celtic v Benfica; Shakhtar Donetsk v Milan. 28 Nov: Benfica v Milan; Celtic v Shakhtar Donetsk. 4 Dec: Milan v Celtic; Shakhtar Donetsk v Benfica.