Mauricio Pochettino says Romeo Lavia could make his Chelsea debut against Wolves on Sunday but warned his returning injured players that they will be phased in very slowly.
The Argentine was keen to send a message directly to his Blues squad that he will only pick players who are fully fit and in good form.
Lavia, 19, has not played a competitive match for almost seven months now and has yet to make his Chelsea debut since a £53million summer transfer from Southampton.
Pochettino confirmed his midfielder's availability after he trained in full at Cobham this week, albeit with a warning to the wider squad.
“Lavia is in a similar position to [Christopher] Nkunku," he said. "He arrived and never made his debut. After six months, maybe tomorrow he will be involved, maybe.
"He is with the team and doing well but he still needs time to get his best form.
"They are all desperate to make debuts and we are pushing, but I need to be clear that we cannot make the mistake, they can be involved, but in which form, at what level?
"It is easy to say I want to play but we are competing, and it is serious the competition but, after six months, Nkunku and him need to know they need to train really hard every day, or double the players who are fit, to make an impact when they go to the pitch."
Noni Madueke and Lesley Ugochukwu are also back to full fitness for Chelsea and Nkunku made his own long-awaited debut in the midweek Carabao Cup penalty shootout win over Newcastle.
Pochettino added that those who have been injured can't expect to start matches right away.
"It’s not to say we are in a pre-season game and they go to the pitch and we say, ‘if they perform well, if they don’t perform well, then no problem’, because six months.
“For many things it is an excuse, for many things, ‘I want to play. If I don’t have time I can’t perform, but in the same time, to play with that’. You need to understand, the players need to understand that is not a charity thing; that we are going to play football, we need to win.
“Sometimes the professionals feel so disappointed because they want to play. It’s difficult to understand. The environment of the player, also, they say they are disappointed because Nkunku didn’t play against Sheffield United.
“I am disappointed to have a player that should be an important player for us is not helping the team. If he didn’t play, it is not because we don’t believe in him, or in this case Lavia.
"It is because there are many other players fit and training in six months and in that moment maybe we need to decide, to make an impact with players that are more ready than these guys.
“We are not talking about names, or suppose he is going to be better than one [player]. We are talking about today, who is ready to compete and provide what we are expecting for the team.
"The players need to understand that this is not a charity"
“Maybe I am talking too much. But it’s true. But come on, it’s annoying me. Not you [the journalists]. The people around the player, ‘Oh I wanted to play. I am disappointed’. Oh, come on. I am disappointed.
“The club is disappointed they are investing big to play, to score goals and when you are not scoring goals, okay we pay the salary every month if you don’t play or you are injured. Who suffered for us?
"The coaches. Who suffered for the club? It’s always [this]. No, come on. It’s to get the right balance in this business. It’s so important.”
Midfielder Enzo Fernandez is a major doubt for Sunday after being listed on Chelsea's injury list due to a hernia problem.
Captain Reece James has had surgery on his hamstring amid reoccurring injuries, but Pochettino was unable to confirm that he would be out for four months, as was widely reported following the procedure on Thursday.
"We don't know how long it will be, for sure several weeks, but I don't know if it is months," he added.
"We hope less [than four months], that is my wish for New Year. We cannot say or put the time period. Always, you know, it will be how his body will react to the damage."
