MADRID - Spain international midfielder Mario Suarez could find himself in hot water after seemingly making an offensive remark against Serbian referee Milorad Mazic.
Suarez blasted Mazic following Atletico Madrid's 0-0 draw with bitter neighbours Real Madrid in the Champions League on Tuesday night.
The 28-year-old picked up a booking and will miss next week's second leg through suspension.
But he risks much worse than that after claiming UEFA should not have put a Serbian in charge of such an important match.
"The referee was very bad. You can't have a Serbian in charge of a Champions League quarter-final, that isn't taking it seriously enough," fumed Suarez.
"I hope that in the second-leg the referee will be better with more fluid and normal decisions.
"The referee wasn't up to it, but they made mistakes as we do.
"The game was very evenly balanced, we know each other so well and the tie is still open." Suarez quickly tried to backtrack on social media, taking to Twitter to explain his comments.
"I'd like to apologise if anyone was offended by my words after the match, that wasn't my intention," he said.
"I wanted to say that in a match of this magnitude you should designate a referee from a major league." Real Madrid dominated the first half at the Vicente Calderon stadium but couldn't break the deadlock.
However, coach Carlo Ancelotti challenged his players to match their first-half performance against Atletico Madrid for the full 90 minutes next week.
The European champions have now failed to score in all four visits to the Calderon this season as Atletico extended their unbeaten run over Los Blancos this season to seven games.
However, Real were by far the dominant side in the opening period and would have been out of sight in the tie had it not been for a string of fine saves from Atletico keeper Jan Oblak.
"It is the best of the bad results," said Ancelotti.
"Atletico are one of the best sides in the world defensively and Oblak had a great game.
"I think that in the first-half we deserved more than to be 0-0 at half-time. We need to highlight the performance in the first-half which was fantastic.
"In the second-half, Atletico pressured more and the game was more even.
"It isn't a brilliant result but we have confidence for the return leg, especially based on the first-half performance." Atletico boss Diego Simeone also hailed Oblak's contribution after the Argentine kept faith with the Slovenian despite the return to fitness of Miguel Angel Moya.
"Oblak was great, especially in the chance for (Gareth) Bale, which was the clearest opportunity.
"The best thing was the reaction we had. Any other team that had been damaged as we were in the first-half would have ended up relenting, but in the second-half the game became much closer to what we had imagined at the start."
And Simeone insisted that Atletico's hoodoo over Real won't count for anything come the return leg on April 22 at the Santiago Bernabeu, the scene of Los Rojiblancos first win over Real for 14 years in the Copa del Rey final two seasons ago.
"It doesn't mean anything because the 14 years did not mean anything for the final and we won the Cup. It will be a different game. It is a classic game with the tension and excitement that anyone who loves football likes to see." A second period short on chances was overshadowed by refereeing decisions.
Madrid defender Dani Carvajal was forunate to escape without being sent-off and giving away a penalty for a punch on Mario Mandzukic.