Andres Iniesta expects Manchester City to be challenging for Champions League glory under Pep Guardiola.
Iniesta remains a fulcrum of the era of success Guardiola set in motion in 2008-09 at Barcelona, where the Catalan giants beat Manchester United in the Champions League final to complete a sensational treble.
Guardiola had the better of his latest clash with United in the Premier League on Saturday, as City made it six wins from as many competitive fixtures under his stewardship in a 2-1 victory at Old Trafford.
Next up are Borussia Monchengladbach in Champions League Group C - a section City also share with Barca and Celtic
"When the group was drawn it was inevitable that much would be made about Pep returning to Barcelona again - but that is not what this group is about," Iniesta told Goal.
"It is a group with four very strong teams - and it would be disrespectful to make it all about Pep and Barcelona.
"What Pep has done for the club will always be remembered, but he is the coach of Manchester City now - and I believe with their quality and Pep's leadership they will be a club that will be challenging for the Champions League this season."
Iniesta will put thoughts of that reunion on the backburner, however, with Luis Enrique's side aiming to bounce back from a shock defeat to Alaves over the weekend when they take on the Scottish champions at Camp Nou.
"For the players we are not even thinking about Pep's return, we are focused on Celtic. They are playing some good attacking football, they have a new coach, and from experience we know they always play with spirit," he added.
"They are not going to give us an easy game, we want to start with a win, our focus is on nothing but this game."