Club Brugge lost by a lone goal at the Parc des Princes but they could have salvaged something from the game when they were awarded a 74th minute penalty for Thiago Silva’s foul on Diagne.
Diagne, though not the team’s designated penalty taker, stepped up and had his feeble effort saved by Keylor Navas which left the Belgian side third in Group A on two points.
Diagne will therefore not be available for selection when Club Brugge face Royal Antwerp in the Belgian league on Sunday.
"He'll not appear in my selection for our league match in Antwerp on Sunday," Club Brugge manager Philippe Clement said at a press conference on Friday.
"It was a dumb mistake. A mistake that had consequences for the result and we are all very cross about it."
"This sort of incident leads to emotions and there was a confrontation in the changing room after, but it was verbal and not physical. Diagne realised he made a mistake and did not argue back."
Diagne, who is on loan from Galatasaray, has scored four goals in six league games this season but Clement has offered no assurances about when he will be back in action.
"We have had disciplinary incidents at this club in the past and players have been given a second chance. It is now up to Diagne to show that he accepts and understands the norms and values of our club," the coach added.
"And I will decide in the coming weeks or months for a possible return to the team. There'll also be a very heavy financial penalty."
