French club Paris Saint-Germain say "errors" by the referee contributed to their calamitous defeat to Barcelona at the Camp Nou last week.
The wealthy Ligue 1 club took a four-goal advantage into their second-round, second-leg clash in the Catalan capital, but saw their lead wiped out in a 6-1 defeat that has gone down as the most remarkable comeback in Champions League history.
Now the Parisian club has sent a complaint to Uefa about the referee, according to local media.
The complaint, according to local newspaper Le Parisien, details the "errors" made by German referee Deniz Aytekin.
The newspaper claims: "The objective sought by the Paris bosses is evidently not to get the match replayed, but more to make themselves heard and earn a form of respect."
The referee's performance has received criticism in light of the match, particularly his failure to award PSG a penalty at a crucial stage in the second half.
However PSG's players have also come under scrutiny for their perceived fragility in surrendering such a commanding lead.