Ederson has been spotted leaving the City Ground with his arm in a sling having gone off during Manchester City's win on Sunday.
The City goalkeeper was substituted at half-time in their 2-0 win against Nottingham Forest after picking up the knock.
3
He collided with Forest defender Willy Boly in the box late in the first half and was left holding his arm before receiving treatment.
Ederson continued to play until the break but was then replaced by Stefan Ortega, who played the second half of the game.
It was a worrying sign for Man City fans who will want their No.1 goalkeeper fit for the final few games of the season.
And those worries will have increased post-match after the Brazilian was spotted leaving the stadium with his arm in a sling.
READ MORE ON PREMIER LEAGUE
His left arm was strapped up completely and looked in bad condition as he walked to the team bus.
It has not been confirmed what the injury is, but manager Guardiola gave an update on Ederson after the game.
He told Sky Sports: "Ede is injured, I don't know how long that will be."
The City boss continued: "It doesn't look very good with Ede. We will see tomorrow."
Most read in Football
3
3
Guardiola will want Ederson fit for his side's remaining four games of the campaign as they compete for an unprecedented fourth straight Premier League title.
City are one point behind Arsenal in the title race and have a game in hand which, should they win it, will put them top.
They take on Wolves on Saturday before having three games in eight days scheduled afterwards.
So having key players fit will be crucial, meaning they will be desperate to have Ederson back in action.
If he is ruled out though, Ortega has proved he is capable of replacing him, most recently keeping a clean sheet against Chelsea in the FA Cup semi-finals.