Thomas Tuchel says it was a "difficult decision" to leave Tammy Abraham out of the squad for Sunday's 0-0 draw with Manchester United.
The striker was not part of the 18-man squad as the Blues shared the spoils with United in the Premier League clash at Stamford Bridge.
It is the fourth time he has not featured for the London side this month, having been left on the bench in against Tottenham, Sheffield United and in the Champions League clash with Atletico Madrid.
What has been said?
Tuchel admits that it is a tough time for the 23-year-old, but says there was no place for him in the team this time around.
"Selection. We have 21 strong players and only 18 possible [to be picked]. It is my job to take hard decisions. This was the decision for 18 guys and Tammy was not with the group," he said.
He added at his post-match press conference: "At the moment he is only struggling with my decision. We have a strong squad. We have only Thiago Silva injured that means we have to make hard decisions.
"We can nominate 18 players, plus goalkeepers so it is clear. It was also an unfair decision for Billy Gilmour because Billy played well in the cup and he was very strong in training.
"It was a hard decision. It was about judging the alternatives that we have and we opted for Olivier Giroud to begin, Timo Werner on the bench. We have Kai Havertz who can play as a number nine so there was no need to bring a fourth number nine to the pitch.
"Things are difficult for him. Things are not as easy as they should be for him in the moment and he will get full support. This was the decision."
Is there a way back for Abraham?
But Tuchel insists that the England international can still win his place back if he continues to work hard.
"It is totally natural [for him to be worries]. He has to do exactly what he does, train well, be in a good mood and accept that he is a striker for Chelsea so this is the highest competition in Europe.
"When you play for Chelsea, it is a difficult decision I have to take and I am very very happy when I have to take them because it means everybody is on board. This is what you sign up for if you are a player for Chelsea, a coach for Chelsea that these moments arrive.
"There is no other answer to it other than to accept it and be there for tomorrow to fight for your place in the squad. I am sure he will do it."
Abraham at Chelsea this season
The striker has started 18 of the 30 games in which he has featured for the London side this season.
Having scored six goals in the Premier League, he is the club's top scorer in the competition this season, though he has only scored one in five Champions League matches.