Pep Guardiola fears Ilkay Gundogan could be out for several months with what could prove to be a knee ligament injury.
Gundogan left the pitch in tears during the first half of Manchester City’s 2-0 victory against Watford on Wednesday night.
The Germany international collided with Nordin Amrabat in the 35th minute but attempted to carry on after receiving treatment from City’s medical staff.
He did not appear to be overly affected when he went on a mazy run and played a pass down the line, but sank to the turf nine minutes after the initial collision.
Gundogan was visibly upset on his way off the pitch and Guardiola admitted in his post-match press conference that things look bleak.
"We are going to miss him I think for a long time," he said. "It is the worst news of the day."
Guardiola believes Gundogan may have suffered ligament damage but will wait for further tests on Thursday.
Gundogan dislocated his knee-cap in May and did not return to action until September, and Guardiola admits he is feeling bad about his latest set-back.
"He's sad. So sad," the Catalan added. 'We spoke with him and he said I want to try but when he hangs up and says he cannot follow him we expected it was not good."