![Monica Seles of the United States gestures to the umpire as she questions a line call during her semi-final match against Switzerland's Martina Hingis at the Australian Open in Melbourne January 28. Monica Seles of the United States gestures to the umpire as she questions a line call during her semi-final match against Switzerland's Martina Hingis at the Australian Open in Melbourne January 28.](https://c8.alamy.com/comp/2D5C59M/monica-seles-of-the-united-states-gestures-to-the-umpire-as-she-questions-a-line-call-during-her-semi-final-match-against-switzerlands-martina-hingis-at-the-australian-open-in-melbourne-january-28-hingis-the-defending-champion-won-in-straight-sets-6-2-6-4-mdbjir-2D5C59M.jpg)
Monica Seles of the United States gestures to the umpire as she questions a line call during her semi-final match against Switzerland's Martina Hingis at the Australian Open in Melbourne January 28.
![Maria Sakkari of Greece in action during her first round match of the 2021 Porsche Tennis Grand Prix, WTA 500 tournament on April 19, 2021 at Porsche Arena in Stuttgart, Germany - Maria Sakkari of Greece in action during her first round match of the 2021 Porsche Tennis Grand Prix, WTA 500 tournament on April 19, 2021 at Porsche Arena in Stuttgart, Germany -](https://c8.alamy.com/comp/2F9R3TH/maria-sakkari-of-greece-in-action-during-her-first-round-match-of-the-2021-porsche-tennis-grand-prix-wta-500-tournament-on-april-19-2021-at-porsche-arena-in-stuttgart-germany-photo-rob-prange-spain-dppi-dppi-livemedia-2F9R3TH.jpg)
Maria Sakkari of Greece in action during her first round match of the 2021 Porsche Tennis Grand Prix, WTA 500 tournament on April 19, 2021 at Porsche Arena in Stuttgart, Germany -
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