The Sun says he is set to miss two games after a scan on his groin injury.
The City midfielder, 28, is out until after the international break later this month and has been ruled out of the weekend clash against Wolves and tonight's Champions League clash with Dinamo Zagreb.
De Bruyne was injured after a heavy tackle from Morgan Schneiderlin and while he was taken off the pitch with ten minutes to play.
The former Chelsea star later revealed he was fine, but hasn't suited up for training since.
It's now expected De Bruyne will be sent for further tests to get the bottom of the problem.
The playmaker could also miss Sunday's game against Wolves - but will then have two weeks to prepare for the trip to Crystal Palace on October 19, thanks to the international break.