Guardiola criticised Phillips for being overweight on his return from England World Cup duty in December.

Phillips, a £45m signing from Leeds last summer, has played less than 10 minutes in the Premier League for City.

"I had the feeling last week that he's back," said Guardiola.

"It will maybe be a good lesson for him for the future. I have the feeling that a football player has to be, for 12 months, perfect. Even in holidays you have to be perfect.

"You can enjoy, you can do whatever you want, but you have to be ready because this level is so demanding. You have to play every three days, you have to be fit, and when you're not fit, nothing.

"In the last week, or days, he improved his level. In the Carabao Cup (quarter-final against Southampton on Wednesday) he is going to play and Sunday we will see."

• How to follow the FA Cup third round on the BBC

City beat a depleted Chelsea 1-0 at Stamford Bridge in the league on Thursday.

Although City are likely to be without Aymeric Laporte and Ruben Dias in defence at Etihad Stadium, Chelsea could be without 10 first-team players.

"I've never experienced anything like it," said manager Graham Potter, whose side have lost five of their past eight matches in all competitions.

"There are some challenges we face, there are some margins in the Premier League that are difficult, but we've had a massive transition and problems in terms of injuries which don't make it easy to be stable."

Midfielder Mason Mount may return from a training ground knock, but Raheem Sterling, N'Golo Kante, Reece James, Wesley Fofana, Ben Chilwell and Christian Pulisic are among those sidelined.