The half time of 0 - 1 made the referee suspicious about the reactions that will follow from the players of AEK. And that was right. A lot of tackles, some of them hard, and a lot of talking to the referee, made him really nervous. After the 50th minute the referee lost control. A lot of fouls went unpenalized. Mistakes followed by other mistakes in order to correct previous decisions.
The referee's performance was below expectations. In a nervous game, the referee should have been more strict.