semifinals match against No. 1 seeds Black and Huber. Stosur was one of only two players on tour who played at both year-end championships. The other one was María José Martínez Sánchez, who was in Stosur's group for the round-robin stage with Ágnes Szávay. Stosur won her first match against Szávay in three sets but lost her second to Martínez Sánchez. This loss cost her a semifinal spot as Martínez Sánchez won both round-robin matches. 2010: World's top ten and first singles Grand Slam final Alongside Lleyton Hewitt, Stosur represented Australia at the Hopman Cup. The Australians were the top seeds. Their first tie was against Romania, where Stosur lost to Sorana Cîrstea in a three-setter, and then lost in the mixed doubles. The next tie was against the US, where Stosur beat Melanie Oudin in straight sets. Hewitt also won his singles match against John Isner, sealing the tie. In mixed doubles, Hewitt-Stosur lost. To advance to the final, Australia needed to win their tie against Spain 3–0. This result was, however, reversed, Australia losing to Spain 0–3. Stosur's last preparation tournament prior to the Australian Open was the Medibank International where she lost to Flavia Pennetta in the first round. Stosur was guaranteed a seeding of 13 for the Australian Open. She lost against world No. 1 and defending champion, Serena Williams, in two sets. Despite the loss, she moved up to a career-high ranking of No. 11. She played with Nadia Petrova in the doubles event of the Australian Open. They were seeded fifth, but lost to another Russia-Australian duo, Vera Dushevina and Anastasia Rodionova in the first round. She then travelled to Adelaide to represent Australia at the Fed Cup alongside Alicia Molik, Casey Dellacqua and Rennae Stubbs against Spain. Stosur won both of her singles matches by beating María José Martínez Sánchez and Anabel Medina Garrigues. Stosur and Stubbs also won their doubles match, gifting Australia a 3–2 win in the tie. Her next tournament was the Dubai Championships where she was seeded ninth. Stosur was defeated in the opening round, at the hands of veteran Tathiana Garbin. She had better success in the doubles partnering Petrova. The pair was seeded fourth and reached the semifinals after receiving a first-round bye, then a walkover, and a win against fifth seeds Alisa Kleybanova and Francesca Schiavone. Seeded eighth at the BNP Paribas Open, Stosur received a