The 25-year-old seemed set to become one of the greatest players the sport has ever seen but decided to call it quits.
Swiatek clinched the top spot with a 6-2, 6-0 victory over Viktorija Golubic of Switzerland in the second round of the Miami Open.
Ash Barty unexpectedly withdrew from tennis at the age of 25 when ranked No. 1 and less than two months after winning her third Grand Slam singles championship at the Australian Op...
Ash Barty won the match 6-3, 7-6 (7-2) to end a 44-year wait for an Australian to win their home Grand Slam.
Swiatek, who was defeated by the American 6-4 6-1 in 78 minutes, also advanced to the semi-finals of the tune-up event in Adelaide.
Ash Barty and Alexander Zverev won the Western and Southern Open tiitle
Australia's Ash Barty is out of the Olympics women's singles after being dumped in straight sets by Spain's Sara Sorribes Tormo, 6-4, 6-3.
Top seed Ash Barty enters quarterfinals after a hard-fought win against Shelby Rogers, but Petra Kvitova, Garbine Muguruza are out
Ash Barty eases past Elina Svitolina in semifinals and is in touching distance of retaining her Miami title