The Spanish midfielder was part of the team that won La Liga, the Champions League and the Copa del Rey last term, before he moved on to Al Sadd to begin the next chapter of his career.
The 35-year-old has said that the team he left is still the best in European football and has backed the Catalan club to enjoy more trophies this term.
"They have the team to re-win the treble and Luis Enrique is a great coach, a perfectionist, very methodical and a great leader," Marca quotes Xavi as saying.
"Barca can now enjoy the best players in the world. But it will be difficult. From the heart I hope they repeat the Champions League and get all the success they want."
Xavi represented Barcelona between 1991 and 2015.