Pep Guardiola could be without top scorer Sergio Aguero for a significant length of time – conceding the Manchester City striker's knee injury "doesn't look good".
Aguero's setback in winning a first-half penalty was a solitary but significant blot on City's work in a dominant 5-0 win over Burnley at the Etihad Stadium.
Guardiola was unsure of the exact diagnosis but told Sky Sports the Argentina international had been nursing soreness in his knee, which appeared to be aggravated in a challenge with Burnley skipper Ben Mee.
"That doesn't look good. Something in the knee, so we'll see tomorrow," the City manager said.
"He felt something in his knee and he struggled in the last month with some pain in his knee, so we will see.
"I'm not a doctor, but it doesn't look good."
Riyad Mahrez claimed his second goal of the match from the penalty spot and Phil Foden also helped himself to a brace after David Silva got in on the act.
Aguero has scored 23 times in all competitions this season, with his 16 Premier League strikes coming at a rate of one every 91 minutes.