Czech tennis players Barbora Krejčíková and Kateřina Siniaková have formed a successful doubles tennis partnership since 2013. They have won seven major tournaments and seven other Women's Tennis Association (WTA) titles. With additional wins at the 2020 Olympics and the 2021 WTA Finals, they are the only women's doubles team to complete the career Super Slam jointly. Siniaková and Krejčíková are respectively ranked by the WTA No. 1 and No. 2 in doubles . History 2013–2017: Junior success and early professional years In 2013, Krejčíková and Siniaková, both aged 17, won three of the year's four junior Grand Slam doubles tournaments. They were paired together when each of them "couldn't find a partner" for doubles at the French Open, and went on to win the event without dropping a set. A month later, they repeated the feat at Wimbledon, and they completed their junior careers with the same result at the US Open. Including two other tournament wins, this stretched their team win–loss record at junior events to 24–0 (48–0 in sets). Siniaková and Krejčíková had peak junior International Tennis Federation (ITF) rankings of No. 2 and No. 3 respectively. Following their junior triumphs, the team played intermittently from 2014 to 2017. Siniaková was the first to establish herself on the WTA Tour, cracking the top 50 in singles in 2016, while Krejčíková initially struggled, not reaching the top 100 in singles until 2020. This gap in rankings sometimes made it difficult for them to enter the same tournaments, but they did manage to play at several events together in 2016. At the French Open, on the way to their first major women's doubles semifinal, they beat the team of Martina Hingis and Sania Mirza that was attempting to finish a non-calendar-year Grand Slam. They additionally reached the quarterfinals of the US Open. 2018–2020: first Grand Slam titles, Fed Cup win, No. 1 ranking After a break of more than a year, Krejčíková and Siniaková reunited in 2018. Early that year, they reached their first two WTA Tour doubles finals as a pair in Shenzhen and Miami. In the summer, they reached and won their first Grand Slam finals together: At the French Open, they beat the Japanese pair Eri Hozumi/Makoto Ninomiya in a quick straight-set final, and in the Wimbledon final, they outlasted Nicole Melichar/Květa Peschke . These wins made Krejčíková/Siniaková the first doubles team to complete the Channel