Mauricio Pochettino explained his decision to leave Armando Broja out of the starting XI as Chelsea lost the first leg of their Carabao Cup semi-final at Middlesbrough.
Midfielder Hayden Hackney scored the only goal at the Riverside Stadium in a 1-0 win for the hosts on Tuesday night.
Pochettino opted to play Cole Palmer as a false nine, with Nicolas Jackson at the African Cup of Nations.
Asked why Broja didn't start, after the Blues failed to score against Championship opposition, Pochettino said: "Armando played after 60 minutes and also we cannot create too many chances.
"I think you need to understand that now you cannot say it was one player or another. Armando came from one year out injured and in this period was playing a few days ago.
"He cannot start like a normal player. We need to manage and in three days we have another game he should start. It's difficult for a player like this to start three games in seven days. That is why, yes.
"When he came to the pitch with Mischa [Mudryk], it was difficult for them to connect, difficult to create chances and in the end they cannot help to score or take a different result."
Palmer was guilty of missing the best Chelsea chances, with those all coming before the break.
The Blues were flat in the second half, but Pochettino refused to be harsh on his players and insisted they deserved to win.
"We were punished because of some mistakes we made in the first half," he said.
"I think we are agreed that we concede a goal because of our mistakes. Few mistakes that we made, we were punished and they took advantage of that.
"We create chances enough to score and draw in the end. If we assess the game after 90 minutes I think we were the better side but if you don't score goals you cannot win.
"Credit to Middlesbrough because they were aggressive and they create chances and score and we didn't score.
"It's the first 90 minutes, first half of the tie and we are losing 1-0. In 15 days we are going to have the second tie and we need to be positive we can win the game and go to the final."
