Xavi said his Barcelona side suffered “a real injustice” after a 1-0 loss at Inter Milan left them in danger of a second successive group-stage elimination in the Champions League.
Hakan Calhanoglu’s strike in first-half stoppage time gave Inter victory.
Barca thought they had rescued a point when Pedri scored in the second half, but it was ruled out by video assistant referee for an Ansu Fati handball.
Defeat leaves Barcelona third in Group C, three points behind Inter.
It was a night of controversy at the San Siro from VAR decisions, the most notable incident coming when Pedri appeared to have equalised on 67 minutes after Cameroon keeper Andre Onana came through a crowd of players and palmed a cross straight to him, allowing the 19-year-old to finish.
However, Fati had his hand raised and the ball was pushed into his fingers at point-blank range as he put Onana under pressure. The goal was ruled out via VAR, and Barcelona manager Xavi was booked for complaining to the referee.
“The referee should be out here explaining why he makes these decisions, if he made mistakes or not. That would humanise them a lot more,” said Xavi.
“Today I’m really unhappy. I feel there is real injustice.”
Before the match, it was Xavi’s Inter counterpart Simone Inzaghi who was under pressure. His team are ninth in Serie A after losing four of their eight league games this season.
He had the additional headache of facing in-form Robert Lewandowski, who had scored nine goals in his past seven games for Barca, although he had never netted at the San Siro.
It is a barren run that continued for Lewandowski as he endured a quiet night in Milan, while Inzaghi celebrated a key win that puts Inter in the driving seat for a place in the knockout stage.