Ilkay Gündogan has told ESPN he "didn't know anything about football" before working with Pep Guardiola, while also praising new boss Xavi Hernández as "amazing" and his Barcelona team as having "huge potential."
He won five league titles, two FA Cups, four League Cups and the Champions League during his time in Manchester, culminating in last season's historic treble.
"Before I joined Man City, I thought I knew football," Gündogan told ESPN on Monday. "I was 25 or 26 years old, I'd seen a lot. I'd played a Champions League final. But now standing here after seven years of Pep's school, I'd say I didn't know anything about football before. His influence on the team and me personally was immense."
Gündogan described last season's triumph as "dreamland" but said it was the right time to move, arguing that "if I want to challenge myself and get out of my comfort zone, this is the time."
The Germany international added: "Since I was a child I just adored Barcelona. With players like Ronaldinho and [Lionel] Messi, and then [Sergio] Busquets, [Andres] Iniesta, Xavi... I always said to myself that when I got the opportunity one day, I didn't want to miss out."
"My first impressions [of Xavi] were amazing, exactly what I expected," Gündogan said. "We spoke before the transfer on the phone and he explained a few things to me, his idea [of football], which is quite similar to Man City... We already have a great bond and it's just going to get better."
"I've known [Robert Lewandowski] for a long time," he said, when asked about his new teammates. "I know [goalkeeper] Marc [ter Stegen]... There's a lot of quality in the team, a lot of young players with huge potential."
"I see my role as helping them and allowing them to shine on the pitch," he said, when asked about the latter pair. "Frenkie is still very young too... I think I can be someone who can help them and guide them a little bit, and try to make them express themselves even more."
"[El Clásico is] the biggest game in the world," Gündogan said. "Over the last seven years, and even before when I was in Germany, when it was El Clásico everyone who loves football was in front of the TV. It's maybe the most prestigious game in world football."
"[Bellingham] has shown at such a young age how much quality he has," Gündogan said. "He's impressive... With his work off the ball and his physicality, he combines a lot of things that a modern midfielder needs. And he also scores goals. He has a lot to offer."