Pep Guardiola says Vincent Kompany will be out for "weeks" with a knee injury.
Kompany was withdrawn during the first half of Manchester City's 2-1 victory at Crystal Palace on Saturday following a collision with goalkeeper Claudio Bravo.
Guardiola initially feared Kompany had suffered a head injury, but that is not the case.
However, the City boss has revealed that the centre-back has injured his knee, and his "sad" about his latest set-back.
"He's injured," the City boss said ahead of City's Champions League game against Borussia Monchengladbach. "Fortunately there is nothing wrong with the head, but it is his knee.