Slam since Kim Clijsters/Ai Sugiyama in 2003. The pair nearly replicated their junior triple as the top-seeded team at the US Open, but lost in the semifinals to eventual champions Ashleigh Barty/CoCo Vandeweghe. Krejčíková and Siniaková were the first team in 2019 to qualify for the season-ending WTA Finals, where on their debut in October they finished runners-up to Tímea Babos and Kristina Mladenovic. Shortly before season's end, the team jointly attained the No. 1 ranking for the first time. Additionally, they were named the WTA Doubles Team of the Year. The next year, Krejčíková and Siniaková qualified for the WTA Finals for a second straight year but did not win any major titles in 2019. They won two tournaments this year, the Rogers Cup in Canada and the Linz Open in Austria. Elise Mertens and Aryna Sabalenka beat them in the Indian Wells final. At the majors, the Czechs lost in the quarterfinals of the Australian Open to eventual champions Samantha Stosur/Zhang Shuai; as defending champions and top seeds, they lost in the first round of the French Open; and they reached the semifinals of Wimbledon, where they lost to Gabriela Dabrowski/Xu Yifan. They fell in round-robin play at the WTA Finals. In the 2020 season disrupted by the COVID-19 pandemic, Krejčíková and Siniaková reached at least the semifinals of all six events they entered together. Their only title this year came at the Shenzhen Open. In major play, the team's run to the Australian Open semifinals was ended by No. 1 seeds Hsieh Su-wei/Barbora Strýcová, and they lost the French Open semifinal to eventual champions Babos/Mladenovic. The WTA Finals were cancelled this year. 2021–present: return to No. 1, Olympic gold, career Grand Slam In a "resurgent" season in 2021, Krejčíková and Siniaková won multiple important titles. In February, they started strong by taking home the Gippsland Trophy in Australia and finishing runners-up at the Australian Open to Mertens/Sabalenka. While they lost in the early rounds of several spring hardcourt events, on the clay in Madrid they won the doubles title over Dabrowski and Demi Schuurs . In June, Krejčíková turned in a historic performance at 2021 French Open, becoming the first player to win the tournament in singles and doubles simultaneously since Mary Pierce in 2000. This event, in which Krejčíková saved a match point, marked her rise to prominence in singles. In the doubles final, she and