she played as the fourth seed, and after defeating Evgeniya Rodina, she lost in the second round to qualifier Beatriz Haddad Maia. In Madrid, Stosur lost in the third round to the fourth seed Simona Halep, having defeated Sara Sorribes Tormo and Mariana Duque Mariño. Then in Rome Stosur lost in the first round to Anastasia Pavlyuchenkova. Stosur won her ninth WTA title in Strasbourg, defeating fellow Australian Daria Gavrilova in the final. The heavily disputed match between the two Australians lasted 2 hours and 45 minutes. She then began her campaign at the French Open to try and defend her semifinalist points from last year. She defeated Kristína Kučová in the first round, in straight sets, to advance to the second round where she beat former world No. 13, Kirsten Flipkens, in straight sets to advance to the third round. She then defeated Bethanie Mattek-Sands in straight sets but lost in the fourth round to eventual champion Jeļena Ostapenko. This resulted in her losing her Australian women's No. 1 ranking to Daria Gavrilova. And, unfortunately, Stosur missed the grass-court season because of a stress fracture in her hand. 2018: First doubles title in five years At the Australian Open, Stosur lost in the first round to Monica Puig despite having match point in the second set. She also failed to defend her title at the Internationaux de Strasbourg, losing to Dominika Cibulková in the quarterfinals of the tournament. At the French Open, Stosur lost in the third round to Garbiñe Muguruza. In Mallorca, Stosur reached the semifinals where she lost to Sevastova. At Wimbledon, she lost in the second round to fellow Australian Daria Gavrilova. At the US Open, she was defeated in round one by second seed Caroline Wozniacki. 2019: Australian Open doubles title Stosur competed with Zhang Shuai at the Australian Open. In the second round, they defeated eighth seeds Hsieh Su-wei and Abigail Spears, and in the quarterfinals, they beat top seeds Barbora Krejčíková & Kateřina Siniaková. They advanced to the final, where they defeated second seeds and defending champions, Kristina Mladenovic and Tímea Babos, to win the championship. This was Stosur's first Grand Slam title since the 2014 Wimbledon mixed-doubles title and her first in women's doubles since the 2006 French Open. 2021: Western & Southern Open and US Open doubles titles Stosur started her 2021 season at the first edition of the Yarra Valley