In December 2023, he was hospitalised after being attacked at the end of a Süper Lig match between MKE Ankaragücü and Çaykur Rizespor, an incident that led to a week-long suspension of all Turkish league football.

[4][5][6] On 9 December 2020, he officiated his first UEFA Champions League match, between Manchester City and Marseille, in which the English side won 3–0.

[8][9] In May 2023, he refereed the first leg of the 2022–23 UEFA Europa Conference League semi-finals between West Ham United and AZ Alkmaar.

"[20][21][22] Meler, who was expected to remain in hospital for a second night, was reported by medical staff to have sustained a facial fracture and a bleeding to his eye but that there should be no permanent damage.

[23] The Turkish Football Federation (TFF) convened an emergency meeting after the incident; the Süper Lig was subsequently indefinitely suspended.

[24][25] Ankara Western Chief Public Prosecutor's Office started an investigation into the incident and issued a detention warrant for Koca and two other people.

[28][29] A day after the incident, Koca apologized to Meler and his family in a press statement in which he also announced his resignation as the Ankaragücü club president.

[34][35][36] On the same day, in a press conference held in Istanbul, TFF president Mehmet Büyükekşi denied all allegations of Meler quitting refereeing due to the attack.

In the same press conference, Büyükekşi said the Turkish football leagues would resume on 19 December 2023, ending a week-long suspension following the attack.

[37] On 20 December 2023, Meler stated that MKE Ankaragücü coach Emre Belözoğlu had provoked the attack and claimed that he had a grudge against him from the past.

Although Koca appeared in front of the judge on 9 January 2024, Koca's trial without arrest, which was supposed to take place on the same day on charges of injuring a public official, threatening an official and violating a law relating to the prevention of violence in sports was adjourned to 28 February 2024.

[46] FIFA president Gianni Infantino also condemned the attack, calling it "totally unacceptable," and adding "without match officials there is no football".