After suffering with illness earlier this year, Grealish was handed just his second start of 2024 in City's 3-1 win over Copenhagen in the first leg of their Champions League last-16 tie on Tuesday.
However, the attacker was forced off in the 21st minute with an apparent groin problem following a collision with Copenhagen's Diogo Goncalves; Grealish initially attempted to carry on but eventually limped off down the tunnel.
Guardiola revealed after the match that Grealish has sustained a «muscular» injury and club doctors have since informed him that the Englishman will not be fit to feature against Chelsea this weekend.
Speaking at a press conference on Friday, Guardiola said: «Jack I think will not be ready. I don't know [his condition]. I need to speak with the doctors. I only know he is not able to play tomorrow.»
Grealish's injury is not thought to be a serious one, and according to The Telegraph journalist Mike McGrath, the attacker is expected to be ruled out for two to three weeks.
The 28-year-old will be joined in the treatment room by defender Josko Gvardiol, who is also sidelined for two to three weeks with an ankle ligament injury.
Like Grealish, Bernardo Silva was also withdrawn in the midweek win against Copenhagen after picking up a «big knock» to his ankle midway through the second half.
However, Guardiola has confirmed that the playmaker will be assessed in training on Friday afternoon and therefore has a chance of featuring in Saturday's matchday squad.
Meanwhile, Mateo Kovacic and Sergio Gomez have both returned to training on Friday and are in
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