Manchester City left-back Oleksandr Zinchenko will be out for up to six weeks after undergoing a procedure at a Barcelona hospital.
The Ukrainian posted an image on social media caption of himself lying in a hospital bed, appearing to be recovering from surgery, with the caption "on the way back" on Friday.
Zinchenko missed the Champions League win over Atalanta on Tuesday and manager Pep Guardiola later revealed the time-frame involved.
Guardiola said: "He had a contact with the knee and felt something in the bone. He's had to stop for four or five weeks.
"He's had some surgery to clean up the knee. It's not a big issue but he'll be out for five or six weeks."
Guardiola also confirmed Rodri will spend an extended spell on the sidelines after he was forced off with an apparent hamstring problem in midweek.
"They told me after the international break he will be ready again," he said of the Spain international.
His absence will come as a blow for Guardiola, who already has Aymeric Laporte and Leroy Sane out long term with serious knee injuries.
Zinchenko has established himself as first-choice left-back over Benjamin Mendy - but the France international provides established over for Guardiola as his side look to chase down Premier League-leaders Liverpool.
Laporte, meanwhile, has not played since being stretchered off in August and it is not known when he will return to the first-team fold, while Sane is not due back until 2020.