City's new £60m signing from was taken off injured in the first half.
Guardiola did not know about the condition of Mahrez.
Pep Guardiola was unable to provide any details about the extent of Riyad Mahrez's injury.
The Algeria international who secured a move from Leicester City to the Etihad this summer got injured in Man City's 3-2 win over Bayern Munich.
The Citizens sealed the win as they fought back from two goals down against the Bundesliga champions.
Speaking after the match, Guardiola said he did not know about the condition of his £60m signing,
"I don't know [the extent]. I wasn't in the locker room. It was his ankle. We will see, maybe it is not a problem," he said as Goal reported.
"I'm concerned for many things, for injured players, players who are still not here but I am so satisfied for what all of the guys on the tour have done."