Referee Wolfgang Stark made several contentious calls in the first leg of their Champions League quarter-final on Tuesday, including allowing Zlatan Ibrahimovic's goal from an offside position to stand and awarding Barca a penalty in stoppage time after Alexis Sanchez was impeded by Salvatore Sirigu.

The Ibrahimovic incident particularly riled Roura, and he told reporters: "I hear that Ibrahimovic was clearly offside when he scored, by a few feet too.

"I remember what happened to us in our last match (against AC Milan in the round of 16). One goal came from a blatant handball, but the referee did not see it. And today, there were several refereeing decisions that were questionable."

Midfielder Sergio Busquets also echoed his trainer's sentiments, adding: "It is impossible that the referee did not see it (Ibrahimovic's goal), because he was one or two metres off."

But Andres Iniesta was in a more understanding mood towards Stark's performance, and preferred to focus on the positives of his team’s display.

"Did the referee decide the outcome? Football is full of mistakes and difficult decisions. Apart from that, our team played a great game," said the 28-year-old.

The second leg is at Camp Nou in eight days, but Barcelona will be waiting on the fitness of Lionel Messi, who picked up a hamstring injury and departed during the half-time break.