Samantha Jane Stosur (born 30 March 1984) is an Australian former professional tennis player. She was a world No. 1 in doubles, a ranking which she first achieved on 6 February 2006 and held for 61 consecutive weeks. Also a former top ten singles player, Stosur reached a career-high singles ranking of world No. 4 on 21 February 2011 and spent a total of 165 weeks ranked inside the top ten, between March 2010 and June 2013. Stosur was also the top-ranked Australian singles player for 452 consecutive weeks, from October 2008 to June 2017, and was ranked inside the top 25 for a period of nine straight years. She won a combined total of 40 career titles (9 in singles, 28 in doubles, and 3 in mixed doubles), including eight major titles, and amassed more than $20 million in prize money. Stosur won a major singles title at the 2011 US Open, where she beat Serena Williams in the final and became the first Australian woman since Evonne Goolagong Cawley in 1980 to win a Grand Slam tournament. She had previously reached another major singles final at the 2010 French Open, along the way defeating former world No. 1 and four-time champion Justine Henin in the fourth round, ending the Belgian's 24-match winning streak at the tournament, and then-world No. 1 Serena Williams in the quarterfinals, before losing to Francesca Schiavone. Her other major singles achievements include two semifinal finishes at the WTA Finals in 2010 and 2011, as well as reaching three WTA 1000 finals (the Italian Open and Canadian Open in 2011, and the Qatar Open in 2012) and the final of the WTA Elite Trophy in 2013. She also reached the semifinals of the French Open in 2009, 2012 and 2016, and the US Open quarterfinals in 2010 and 2012. Stosur is a four-time major champion in women's doubles, winning the 2005 US Open and 2006 French Open with Lisa Raymond, and the 2019 Australian Open and 2021 US Open with Zhang Shuai, and reaching an additional five major finals (three with Raymond, one with compatriot Rennae Stubbs, and one with Sabine Lisicki). She won back-to-back WTA Tour Championships doubles titles with Raymond in 2005 and 2006, and was the co-year end world No. 1 with Raymond in 2006. Stosur has also won three mixed-doubles Grand Slam tournament titles, at the 2005 Australian Open with Scott Draper, the 2008 Wimbledon Championships with Bob Bryan, and the 2014 Wimbledon Championships with Nenad Zimonjić.