The Sly Blues now face an uphill task to make the quarter-finals after slipping to defeat at home to the La Liga giants in a tightly contested game at the Etihad Stadium.
The decisive moment of the tie came after 53 minutes, when Martin Demichelis saw red for a foul on Lionel Messi that resulted in a penalty kick – which the Argentine superstar converted.
The decision was shrouded in controversy, with the challenge appearing to start outside of the area after Jesus Navas was, arguably, also on the receiving end of an illegal tackle in the build-up to the incident.
Pellegrini was infuriated by Eriksson’s performance, and believes that the referee cost his side the game:
“Of course I have a complaint, not only for the penalty and the red card,” he told Sky Sports.
“I think in the whole match we didn’t have a referee with impartiality to both teams.
“He decided the game. He decided the game because it was a foul by (Sergio) Busquets on Navas. The referee was three metres away and he didn’t blow the whistle and after that the foul from Demichelis is outside the box, it’s not a penalty.
“Important mistakes against a great team like Barcelona make it difficult to win.”
After Messi converted from the penalty spot, Dani Alves added a potentially decisive second away goal with just minutes on the clock.