"It wasn't the pitch or the FIFA virus, our opponent was simply better," the 39-year-old said. "We just need to take on board that things are not that easy and hopefully that will help us focus better.

"Our players are of an exceptionally high level and I will not let them drop their performance for a moment."

The Catalans' defeat was their first at Camp Nou in around 16 months. Guardiola remains optimistic though.

"This doesn't mean we have to worry," Guardiola said, adding that the team had to focus on Tuesday's Champions League group match at home to Greek side Panathinaikos.

"We are facing a difficult year, a tough year, so we have to pick ourselves up quickly both mentally and physically.

"We were lacking in rhythm today. They closed us down very well and it's hard to attack teams that work together so effectively."