The German referee Deniz Aytekin will oversee Atlético de Madrid-Qarabag in the fourth matchday of Champions League's Group C. On the other hand, the British Anthony Taylor will do the same at Olympiacos-Barcelona game,Group D.
Aytekin, who will oversee the game with his compatriots Guido Kleve and Markus Hacker, was the referee of Barcelona-PSG, in the second game of last season's eighth-finals, where Barcelona made it 6-1 securing a great come-back. The German referee received many critics for taking some controversial decisions at that game. Since then, he has only overseen one Champions League match: NK Maribor-Spartak Moscow, Group E.
Gary Beswick and Adam Nunn will help Anthony Taylor to referee Olympiacos-Barcelona. He has only overseen Oporto-Besiktas in 2017-2018 Champions League so far. Two years ago, he was the ref of an Atlético Madrid game in this competition.