Pep Guardiola said that Sergio Aguero could miss the remainder of the season after hobbling off at the Etihad.
The Argentine started for Manchester City in their 5-0 win over Burnley on Monday night.
But after Aguero won a penalty, thanks to the VAR, following a foul by Ben Mee, the striker was taken off in first-half injury time.
After the contest Guardiola confirmed that his leading marksman had been struggling over the past four weeks and feared the worst ahead of further assessment.
"It doesn't look good," said the Catalan. "We will see tomorrow. He was struggling with it the last month. We will see tomorrow but it doesn't look good for this season."
Aguero has scored 23 times in all competitions for the treble chasing side.
City have already landed the Carabao Cup for a third successive season and could still add the FA Cup and the Champions League.
But missing Aguero would be a major blow to Guardiola, who could yet lead the club to an impressive year despite surrendering their title.
The 32-year-old, who is now in his ninth year at the Etihad, has enjoyed a record breaking campaign.
His hat-trick against Aston Villa in January was his 12th treble in the Premier League - a new record.
Gabriel Jesus will fill the void having shared the centre forward role in recent years.
The Brazilian failed to get on the score sheet against Burnley and offers a different kind of threat to his team-mate.
He has scored 18 times for City this term and may have to step up should Aguero's injury rule him out for the season.
