Pep Guardiola is confident Kalvin Phillips is back to full fitness, having described the midfielder as 'overweight' following his return to Manchester City from the World Cup.
Phillips played twice for England in Qatar, coming on as a substitute against Wales and Senegal, but Guardiola was not entirely satisfied with his condition upon his return.
Having struggled with a shoulder injury during the first part of the season, which limited him to just one Premier League appearance, Phillips had to endure an extended wait to return for his second involvement in the league.
That came in Thursday's 1-0 Premier League triumph over Chelsea, where he was introduced off the bench in the 86th minute, and he is now pushing to make his first City start in the FA Cup against the Blues on Sunday.
While Guardiola is unsure whether he will be handed that opportunity, he believes Phillips is back in his best shape.
"I don't know whether Kalvin will play, on Sunday we will see. I had a good feeling last week, that he's back," he told reporters.
"He wanted to change our mind with the way he's going to play, maybe it will be a good lesson for him in the future.
"I have the feeling that a football player, for 12 months, has to be perfect, even on holiday. You can enjoy and do what you want but you must be ready because this game is so demanding.
"Last season with Leeds, for long parts he was injured, he came and couldn't train, he struggled with his shoulder. He fought to go to the World Cup, he got it.
"It was a long period without playing, without rhythm that was not there for five or six years. We need Kalvin, we need all the players."
Having beaten Chelsea in the Premier League, Guardiola is aware the Blues could change their approach for the FA Cup tie – particularly having been ravaged by injury issues, losing both Raheem Sterling and Christian Pulisic in the early stages of Thursday's game.
"It is better for us to play Chelsea at home with our fans, after a victory it is much better," he added.
"It will be a different game, maybe Graham [Potter] will change his shape, I know they are struggling with injuries. We have three days to think about it."