Barcelona coach Xavi Hernandez claimed the referee's decision to send Ronald Araujo off in their Champions League knock-out by Paris Saint-Germain on Tuesday was "unnecessary" and ended the club's hopes.

Araujo was dismissed in the 29th minute for pulling down Bradley Barcola on the edge of the box with Barcelona leading 1-0 on the night and 4-2 on aggregate.

With Barcelona down to 10 men, PSG battled back and triumphed 4-1 at Montjuic, progressing 6-4 on aggregate.

"It's a shame that the work of a whole season ends here because of a refereeing decision," Xavi told Movistar.

"This dismissal is unnecessary."

Xavi was sent off for a show of dissent on the sideline as Barcelona lost their heads in the second half and he criticised Romanian referee Istvan Kovacs.

"The referee was very bad, I told him, he didn't understand the game," said the coach.

Araujo's red card led Xavi to take off 16-year-old winger Lamine Yamal, who created Barcelona's opening goal for Raphinha, with Inigo Martinez coming on to fill the hole in defence.

"We're angry, the red card defines the tie," continued Xavi.

"We were well organised, for me it's too much to give a red card, from there it's another tie.

"We had doubts about whether to take off Lamine, he was doing well -- that moment completely defined the tie."

Barcelona are eight points behind Real Madrid in the La Liga title race and face Los Blancos on Sunday at the Santiago Bernabeu.

"Right now, thinking about Sunday's game isn't the thing to do," said goalkeeper Marc-Andre ter Stegen.

"We have to rest, charge our batteries and try to feel good again, above all mentally."