Stones had just returned after missing 11 of City's first 12 matches, only to be replaced at halftime during their 3-0 win over Young Boys in a Champions League on Tuesday.

Guardiola said after the game that the defender had aggravated the injury but he sounded more hopeful on Friday.

"The doctor said to me it's not as bad, but still I don't know," Guardiola said.

Defender Manuel Akanji trained on Friday, dispelling injury concerns hanging over him.

"(He is) Good. Trained today and trained good," Guardiola said.

Champions City climbed back to the top of the Premier League table last weekend on 27 points after 11 matches, one point clear of Tottenham. Chelsea are 10th with 15 points, but are coming off a huge 4-1 win at Spurs.

"They are aggressive and have good patterns," Guardiola said of Chelsea. "They are not close to winning the Premier League (at the moment) but it's one of the strongest teams and one of the toughest games we have during the season.

"They showed in the last game they are alive, have spirit and are aggressive. (We will) try to maintain the level of our game but sooner or later Chelsea will be there fighting for titles (again), no doubt about that."

City's Kevin de Bruyne, who has yet to play this season after undergoing surgery on his hamstring injury, was scheduled to undergo a scan this week.

"I spoke with him and he said he feels really good. He's not training with us and I don't know (when he will return)," Guardiola said.

"With this kind of injury it's better we don't put pressure on. Kevin was a bad injury with surgeries so it's step by step."