Jose Mourinho admitted John Terry was not "dancing in the dressing room" after being substituted so the Chelsea manager could bring on a quicker defender in his side's 3-0 defeat to Manchester City.
The Portuguese removed his captain at half-time at the Etihad Stadium and confirmed after the game that Terry, who he had never replaced in 177 previous games under his management, was not injured.
The 34-year-old has been criticised for lacking speed in the past and Mourinho said he wanted to bring on the quicker Kurt Zouma to play with a higher defensive line.
"When you are going to play with a high block, the fastest player has to be on the pitch," Mourinho said in a news conference.
Mourinho did not elaborate on why Terry was taken off, rather than fellow centre-back Gary Cahill, replying: "That is a good question.
"I want to have my fastest player on the pitch and not on the bench. I know they are going to play counter attack and long balls to Aguero. I want to have him on the pitch."
Mourinho said that Terry was not best pleased but did not show dissent at his decision, adding: "He was not dancing in the dressing room and he was not having a bad reaction.
"He did what everybody does. The manager says this guy comes in and that guy goes out and they all understand. They wait for the team, they change or shower and go back to the bench like normal."
The Portuguese said his substitution should not be scrutinised because he has revived Terry's career after he featured less frequently under other managers.
"I don't know if you ask many questions to [Rafa] Benitez, Andre Villas-Boas and Roberto Di Matteo, to the ones that never played him," he said.
"I am the one you shouldn't ask because I am the one who played John every game, made him captain, recovered him from a difficult situation with other managers and had the right to say I want Zouma on the pitch.
"It was clear for me Zouma has to play, then I have to bring one out and I brought my captain and he was on my bench and still the captain because the armband is just the armband."