Uno's figure skating world title defence in doubt after fall
A Japanese team official said Uno would be re-evaluated on Thursday morning - just hours before he is due to perform his short programme in Saitama, north of Tokyo.
The 25-year-old fell in practice and cut short the session as doctors looked at his right ankle.
He was not taken to hospital but a Japanese team official said Uno was already struggling with an ankle issue.
"He says himself that he thinks he's going to be alright but we will look at it again tomorrow," said Japan Skating Federation official Yosuke Takeuchi.
Uno has had a troubled build-up to the competition, telling reporters on Tuesday that he had "doubts" about his ability to defend his title.
"I feel like it's not going to get better unless something big changes," Uno said.
"I don't know what kind of result I can aim for in my present state," he added.
If Uno is fit to skate, he faces competition for the title from American teen and self-proclaimed "QuadGod" Ilia Malinin, France's European champion Adam Siao Him Fa and Canada's Keegan Messing.
The men's short programme is on Thursday and the free skate is on Saturday.
