season, Barty did well at the Premier 5 events, making it to the semifinals at the Canadian Open and the third round at the Cincinnati Open. She lost to world No. 1 Simona Halep at both events. At the US Open, Barty was the 18th seed and reached the fourth round at a Grand Slam tournament for the first time, where she was defeated by Karolína Plíšková. Towards the end of the season, Barty attempted to defend her previous year's finals appearance at the Wuhan Open. Although she was the only seeded player to make the semifinals, she fell one match short against Aryna Sabalenka. Having maintained her top 20 ranking, she was able to qualify for the year-end Elite Trophy for the second straight season. Barty was grouped with Sabalenka and Caroline Garcia and began play by losing to Sabalenka again, while winning eight games. She then defeated Garcia in straight sets while only conceding seven games, meaning she could only advance if Garcia defeated Sabalenka in straight sets while losing at least eight games. Garcia won the group's final match while dropping precisely eight games to send Barty into the knockout rounds. Barty then defeated defending champion Julia Görges and home favourite Wang Qiang to win the biggest title of her career and end the season at a career-high ranking of No. 15 in the world. Doubles: First Grand Slam and Premier Mandatory titles, world No. 5 In 2017, Barty reunited with Dellacqua as her regular doubles partner, and reached the quarterfinals or better at three out of four Grand Slam tournaments during the season. In particular, they made it to the finals at the French Open to become the first Australian women's doubles team to reach all four Grand Slam finals. They lost in the final to the top seeded team of Bethanie Mattek-Sands and Lucie Šafářová, who had also won the previous two majors. Barty and Dellacqua contested six finals on the year in total, winning half of them. They won the Birmingham Classic, where Barty also made it to the final in singles. This was their second career title at the event after winning it in 2013, and also their first Premier title together. Barty and Dellacqua finished the year as the third-highest ranked doubles team, earning them a spot in the WTA Finals. They had narrowly missed qualifying for the event in 2013 when