The Brazilian says he was unsure if leaving AC Milan for Ligue 1 was the right decision but now believes French football is among the best in the world
The defender, 28, left San Siro for an estimated €42 million and - along with fellow ex-Rossoneri team-mate Zlatan Ibrahimovic - helped propel les Parisiens to the Ligue 1 title for the first time in 19 years.
However, the centre-back admits that - at first - he was apprehensive about swapping Serie A for Parc des Princes, but that he has come to perceive French football as amongst the highest quality in the world.
"I had some pretty big doubts when I signed here," the Brazil international - who has been linked with Barcelona throughout the current transfer window - told BeIn Sport.
"Not because of PSG, but because I was leaving AC Milan for a different type of football, what I thought was probably not as good a league.
"Today I'd say the two leagues are on par because Ligue 1 has improved a lot in recent years. This season I think French football will show the world how far it has come, but I had this doubt, I wasn't sure I'd made the right choice.
"I admit that even before we won the title I was still thinking about it. But today I know I made the right choice because I'm working with some formidable people."
PSG started their title defence with a lacklustre 1-1 draw at Montpellier but will hope to bounce back with a win at home to Ajaccio on Sunday, with kick-off at 21:00CET.