Grealish has missed each of the Citizens' last three games against Fulham, West Ham United and Red Star Belgrade after sustaining a knock to his knee in a 2-1 win at Sheffield United at the end of August.
After the 3-1 victory over Red Star in the Champions League on Tuesday, Guardiola stated that the England international may need around seven to 10 days more to recover from his injury.
However, City supporters were boosted by the news that Grealish had returned to training this week, and Guardiola has since confirmed that the attacker could feature against Forest.
The Catalan boss has also delivered a positive update on the fitness of summer signing Mateo Kovacic, who is closing in on a return from a back muscle issue but is unlikely to play on Saturday.
Man City will have to cope without Bernardo Silva, though, as he picked up an unspecified leg injury in the first half of Tuesday's win over Red Star, and the playmaker could be sidelined for up to two weeks, while John Stones (muscle) and Kevin De Bruyne (hamstring) both remain in the treatment room.
Speaking at a press conference on Friday, Guardiola said: «Jack is coming back, training well and could be ready (against Forest).
»[Kovacic] is almost ready, the last part of the recovery but now we lost Bernardo for a few days and John [Stones], Kevin [De Bruyne] are still out.
"[Bernardo is] a little injury, not much. I don't know, a week, two weeks."
The positive news about both Grealish and Kovacic comes after Guardiola stated on Tuesday that his Man City side are «in trouble» due to their mounting injury list.
Guardiola
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