Naomi Osaka retired injured during the Bad Homburg Open final against Karolína Muchová on Saturday.
The former world No. 1 suffered a right ankle injury ahead of Wimbledon.
What happened?
Naomi Osaka was forced to end her match after receiving treatment during the second set.
The Japanese star had earlier shown encouraging signs throughout the grass-court season.
Why it matters for Naomi Osaka
Osaka has endured a difficult relationship with Wimbledon in recent years, missing the 2021 tournament and withdrawing from the 2022 Championships due to an Achilles injury.
She also missed the 2023 edition while pregnant.
What comes next?
Osaka's medical team will continue assessing the severity of the injury before a decision is made regarding her participation.
The former world No. 1 had shown encouraging signs throughout the grass-court season and appeared to be building momentum ahead of Wimbledon.
Naomi Osaka said after retiring: "I'm really sorry I couldn't finish today.
I hope it's nothing too serious and that I'll be able to recover quickly."
The timing of the injury leaves significant uncertainty over whether Naomi Osaka will be fit to compete at the All England Club.
Wimbledon organizers are awaiting an update on her fitness before the tournament begins.
Osaka sustained the injury during the second set after earlier treatment to her ankle.
The discomfort ultimately prevented her from finishing the match.
The Bad Homburg final marked Osaka's first appearance in a grass-court final since returning to the tour.
She produced an encouraging run throughout the week.
Whether Naomi Osaka takes her place in the Wimbledon draw is expected to become clear over the coming days.
Further medical assessments will determine the extent of the ankle injury.
Naomi Osaka's participation at Wimbledon is in serious doubt.
The four-time Grand Slam champion has not officially withdrawn but remains a major doubt for the Championships.