Former women's wheelchair tennis number one Esther Vergeer, who spent 10 years unbeaten, has been diagnosed with breast cancer.
The Dutchwoman won 470 successive matches between 2003 and her retirement in 2013.
Vergeer, 38, broke the news on Twitter but says she is "full of positive energy" and has the support of friends, family and colleagues.
"I will go for it. I am sure I will get through this," she said.
Vergeer finished her career with 42 Grand Slam titles across singles and doubles and seven Paralympic gold medals.