MANCHESTER -- Pep Guardiola believes that John Stones has the potential to be as good as his former Barcelona teammate Ronald Koeman.
Guardiola will come up against his close friend Koeman on Saturday when his Manchester City side face Everton in the Premier League.
It will also see Stones face his former club for the first time since his £47.5m switch to the Etihad in the summer.
The 22-year-old has settled in quickly at his new club and Guardiola has been impressed by the composure and passing ability of the England defender.
He says Stones has room to improve but claims that he could be as good as former Netherlands captain Koeman, whom he describes as "one of the best central defenders I've ever met."
"It's quite similar in that they both like to play the ball," he told a news conference. "Normally a central defender is a big guy, good with their head, mark man-to-man -- and we need that, of course. You need central defenders for that. But now it's a plus if they've got the quality to play.
"John has similarities to Ronald. Especially in the mentality. John is a guy who always wants to play, be under pressure. Normally the players who like to play the ball handle the pressure better than the other ones. I cannot compare them still now, not yet, maybe in the future.
"The long balls of Ronald -- he was the best ever. But John is young enough, he can improve.
"He played with the national team very good. In the last European Championships he didn't play one minute and now he's playing all of the games. He's already he's an important player for the national team and I'm so happy for that."
The two managers remain close friends and have met up on several occasions since taking over at their new clubs, that are just 30 miles apart, in the summer.
They were together for five seasons at the Nou Camp in the 1990s and were roommates as part of Johan Cruyff's "Dream Team" that won four La Liga titles and a European Cup.
And Guardiola says Stones couldn't have a better role model if he wants to become an even better player.
"I think he was one of the first central defenders with the quality not just to defend," the City boss said.
"Johann Cruyff bought Koeman to show us, to teach us why we need a central defender like Ronald.
"He was one of the few guys that I never saw fail in important games -- he always played well. I never saw him play a bad, bad game in the Champions League.
"His quality was the big build-up, amazing long balls, 40 metres, quick balls. By far one of the best central defenders I've ever met."