Paris Saint-Germain have complained to UEFA about the refereeing of their 6-1 Champions League defeat at Barcelona last Wednesday.
The French club are unhappy with the performance of German referee Deniz Aytekin and, in particular, his decision to award Barcelona a controversial late penalty.
The Catalans scored three goals in the final seven minutes to come back from 4-0 down in the first leg to win 6-5 on aggregate.