While the likes of Serena Williams and Rafa Nadal continue to chase Grand Slam titles, defying age and injuries, Barty's declaration that she has achieved everything she set out to in the sport stands in sharp contrast. She leaves tennis as world number one and a three-times major champion with titles at Roland Garros and Wimbledon alongside her Australian Open triumph in January, just when the discussion had moved on to how many more Slams she could win. "There was a perspective shift in me in the second phase of my career that my happiness wasn't dependent on the results," Barty said. "Success for me is knowing I've given absolutely everything I can. I'm fulfilled, I'm happy. I know how much work it takes to bring the best out in yourself... I don't have that in me anymore."