Chelsea midfielder Moiss Caicedo hurt his left ankle during second-half injury time in Tuesday's 2-0 win over Fluminense in the semifinals of the Club World Cup.
Caicedo received treatment, returned to the game, then hobbled off as Chelsea finished a man short.
"Moiss, he twisted his ankle," Chelsea manager Enzo Maresca said.
"I told him, because there were just two, three minutes to go, I told him that we could play with 10 players. The important thing is it was not getting worse, because we have a game on Sunday, but he felt that he could try. But he tried and he felt pain. So hopefully he can be fit on Sunday. We see."
Chelsea will face Real Madrid or Paris Saint-Germain in Sunday's final.
