Thomas Tuchel has confirmed that Timo Werner picked up an injury in the build-up to Saturday's FA Cup final defeat to Liverpool and was left on the bench as a result.
The Blues were already surprisingly without Kai Havertz, whose absence through injury was confirmed when he was left out of the matchday squad, but there was no suggestion of an issue for Werner as the German took his place among the substitutes.
There was some shock from fans as Werner did not enter the game, particularly as both Ruben Loftus-Cheek and Ross Barkley came on before him, with the latter being brought on specifically for the penalty shoot-out at the expense of the former.
Before the controversy could even begin, Tuchel revealed that Werner was injured and unavailable as a result.
"Kai did not train yesterday because of hamstring problems and he thought if he trained he would injure himself," Tuchel explained. "We left it until the last test this morning but it was not possible.
"Timo was injured and uncomfortable during the warm-up and said he could not play."
Fans also watched on as centre-back Thiago Silva played almost the entirety of the 120 minutes with a knee injury which he picked up in a collision with Trevoh Chalobah, with the 37-year-old visibly wincing with every kick of the ball.
"It was clear we would suffer against this team and we managed to stay in the match because of an excellent goalkeeping performance," Tuchel said. "We dug in and got better and better and created chances ourselves.
"Everyone is in pain, there is no way you play this game without pain."
Finally, Tuchel confirmed that Loftus-Cheek, who was subbed on at the start of the second period of extra-time but replaced by Barkley before the 15 minutes were up, was only taken off because of his inferior penalty record.
"That was purely for penalties," he concluded. "Ruben doesn't have a good history and Ross has. So it was down to the penalties."