Liam Rosenior has refused to put a timescale on Estevao's return to action for Chelsea after he was granted compassionate leave to travel to his native Brazil.
The 18-year-old is set to miss Tuesday's League Cup semifinal, second leg away to Arsenal in a blow to the Blues' chances of overturning a 3-2 deficit.
"He's going through a really difficult time for personal reasons, he's on compassionate leave," Rosenior told a pre-match press conference on Monday.
"I won't put any pressure on. It has to be right for him and he has to feel like he's in the right place to perform."
Chelsea came from 2-0 down to snatch a dramatic 3-2 win over West Ham on Saturday and maintain a positive start to Rosenior's reign.
He has won six of his seven games since replacing Enzo Maresca, with the only defeat coming against Arsenal in the first leg three weeks ago.
A big semifinal second leg is coming up next. ✊ pic.twitter.com/gYB792tIJi
— Chelsea FC (@ChelseaFC) February 2, 2026
Rosenior needed a huge impact from his substitutes to turn the game around against West Ham after he rotated his starting line-up following a draining 3-2 away win over Napoli last week.
And he insisted he will have to continue to rotate with Chelsea still involved in four competitions.
"I don't have a best 11," he added. "I never have done at all in all of the clubs I've worked with.
"The physical demands of the Premier League or Ligue 1 or the Championship now, you need a squad. You need to use the players in the correct way to challenge over the course of the season.
"I try and pick the right starting team but I also try and pick a bench that will give us the right finishing team as well.
"So far, the substitutes in every game we've played have made a huge impact. It's not down to my tactical stuff. It's down to their mentality to come on and help the team."