Milos Raonic could miss the ATP Finals because of the leg injury that forced him to withdraw from the Paris Masters on Saturday.
Raonic was scheduled to play Andy Murray in the semifinals but had to withdraw because of a tear in his right thigh from his quarterfinal win over Jo-Wilfried Tsonga.
Raonic said he will need five to 10 days to recover, a delay putting his participation at the ATP Finals in jeopardy. The elite eight-man tournament starts in eight days in London.
"I'm on the borderline for that," the fifth-ranked Raonic said. "I still have a possibility that I might be able to play."