Aleksandr Hleb admits he regrets his time with Barcelona.
The former midfielder, who announced his retirement last week, joined Barca from Arsenal in 2008.
"It was totally my fault [for not succeeding at Barcelona], not [Pep] Guardiola's," Hleb told EFE.
"He did everything possible to help me quickly adapt to the country and the group, and to learn the language.
"I myself behaved like a fool. The group was very good.
"I regret not learning to speak Spanish."
He added: "Guardiola is a great coach, but it is true that it was his debut [season] as a first-team coach.
"He wanted quick success. When eleven players are playing at a high level, you no longer want to make changes."