Elena Baltacha, a former British tennis number one, has died overnight at the age of 30, from liver cancer.
Baltacha, widely known by the nickname Bally, played for Team GB at the London Olympics in 2012, and also thrilled home crowds at Wimbledon.
Born in Ukraine, she moved with her family to the UK and grew up in Scotland.
She had a career troubled by illness and retired from the sport late last year.
Current British number one Laura Robson paid tribute to her friend and team-mate on social media.
She said: "Impossibly sad. Forever a teammate. Sweet dreams Bally."
World number one Serena Williams tweeted: "My deepest prayers, thoughts, concern and love goes out to Elena Baltacha's family. I am deeply sorry for your loss."