Kai Havertz missed the game with a hamstring injury. And when Tuchel considered bringing on Werner late in the game, the striker informed him he had tweaked his own hamstring while warming up.
It led to Ruben Loftus-Cheek being brought on as a makeshift centre forward, before being hooked again after 14 minutes.
Tuchel said: “Timo was injured. He felt uncomfortable in the warm up and said he cannot play.
“Kai did a last test. He did not train because of his hamstring.
“We tried everything and did the last test in the morning, but it was not better.”
Tuchel endured shoot-out defeat to Liverpool for the second time this season after losing the Carabao Cup Final in February.