The 21-year-old Japanese was scheduled to play a semi-final tie against Estonian eighth seed Anett Kontaveit on Saturday evening, but announced in the afternoon that she would be unable to play.

“I don’t expect that I will be able to serve,” she said.

“It’s an ab strain, something that I’ve had before. Thankfully, because I’ve had it so many times I am able to tell what it is and I know what to do.”