Serena Williams has pulled out of the French Open before her fourth-round match with Maria Sharapova because of an injury that affected her severely
The 23-time Grand Slam winner recently returned to tennis after giving birth to her first child, but looked in good form in her opening matches.
"I've had issues with the right pectoral muscle to the point where I can't serve," said the 36-year-old.
"I'll have a scan. I won't know about Wimbledon until I get the results."
Williams said she first felt the problem during her third-round win over German 11th seed Julia Gorges on Saturday.
She played in a doubles match with sister Venus on Sunday, saying she wanted to try to manage the problem before her match with Sharapova.
"I tried lots of taping and support to see how it felt in match circumstances," Williams said.
"It is hard to play when I can't physically serve. I've never had this injury before, I've never felt it in my life and it was so painful.
"I don't know how to manage it."
Williams said she will have an MRI scan in Paris on Tuesday and will stay in the French capital at least until the extent of her injury is clear.
Have your say
More Sports Headlines
- Thomas Partey shortlisted for BBC African Footballer of the Year 2018
- 2018 AWCON: Ghana open campaign with win over Algeria
- Nigeria return to Africa Cup of Nations
- Uganda reach second straight Nations Cup
- AFCON 2019: Morocco and Mali qualify for Cameroon
- Photos: Prez Akufo-Addo surprises Black Stars in camp ahead of Ethiopia clash
- AWCON 2018: Four key players to watch
- U-17 WWC: Two straight wins for Ghana after hard-fought Finland victory
- Former 'Black Queens' players lead 2018 TOTAL AWCON Trophy tour in Accra
- Asante Kotoko policy analyst counts benefits of Soccerex exhibition
- Kenya loses CAS appeal over Women's Nations Cup exclusion
- Nigeria still AWCON favourites, but face tougher task than normal
- Black Queens begin quest for first AWCON title on Saturday
- VAR set to be used in Premier League next season
- Kwesi Appiah defends Ghana's big-name recalls