An on-pitch fight just before half-time during Inter Milan's thrilling Champions League triumph over visitors Barcelona appeared to have been sparked by Inigo Martinez spitting on Francesco Acerbi.
The hosts returned to the San Siro after a breathless first-leg on the road left the tie level at 3-3 going into the decider on Tuesday evening.
It took very little time for Inter to assert their dominance, with Simone Inzaghi's side going ahead via a goal by Lautaro Martinez in the 21st minute.
Inter doubled their lead on the stroke of half-time, with Hakan Calhanoglu stepping up to strike from the spot after he was brought down in the box minutes earlier by Pau Cubarsi.
But as viewers at home watched replayed footage of the penalty decision and Calhanoglu coolly slotting his effort past Wojciech Szczesny, when live action returned the players on the pitch were in disarray.
Members of both sides appeared to be in dispute with the referee Szymon Marciniak, with commentary describing the possibility of VAR intervening to give a red card.
While all 22 players stayed on the pitch, after full-time on the eventual 4-3 classic new footage came to light of Martinez seeming to spit at his rival after the penalty was awarded.
Pictures from the San Siro show Acerbi appealing to Marciniak, with a group of Barcelona players clustered around their team-mate.
Footage from the stadium appears even more damning, with Martinez allegedly spitting towards Acerbi as the Italian runs past him into the box.
Discussing the potential incident after the final whistle, Wayne Rooney on Amazon Prime stressed that if Martinez was found to have spat on his rival, UEFA would be quick to intervene.
'You certainly don't want to see that in a football game or anywhere,' the Manchester United legend said. 'If he has spat, then he'll get a punishment that he'll deserve.'
Co-pundit Daniel Sturridge added: 'Absolutely right. If he's done that, then it's not good - it's not necessary, it's not needed.
'We'll let the people do their job and see if he's actually done it.'
Acerbi, however, had the last laugh - despite no action being taken after the decision went to VAR.
Barcelona came out of the starting blocks quickly as play resumed after the break, with Eric Garcia scoring in the 54th minute, with the fightback well and truly restarted when Dani Olmo provided the equaliser just six minutes later.
Minutes before normal time, Raphina put Barcelona in the lead for the first time in the two-legged tie, their spot in the final all but sewn up.
But just three minutes into added time, Acerbi was laser-focused inside the box to score his first ever European goal at the age of 37.
Extra-time allowed Inter to find the winner through Davide Frattesi, with the Milanese side booking their second Champions League final in three years.