Ashleigh Barty: The Australian announced her retirement at the age of 25 having spent 119 weeks as the world No 1 and after winning three Grand Slam titles. Barty won 15 singles titles and 12 doubles titles, including three Grand Slams, the last of which ended Australia's 44-year wait for a home-grown Australian Open champion. All photos: Getty Images

Barty, Borg, Hingis and other tennis stars who retired early - in pictures