Garrigues and Virginia Ruano Pascual in three sets in the semifinals, but were defeated in the final by fourth seeds Venus and Serena Williams in straight sets. Stosur was also defending the mixed-doubles title with Bob Bryan, but the second seeds were defeated in the quarterfinals by ninth seeds and eventual champions Anna-Lena Grönefeld and Mark Knowles. On the US Open Series in Stanford, Stosur made it into the semifinals after defeating sixth seed Dominika Cibulková, Monica Niculescu and causing a massive upset win over Serena Williams. She lost to eighth seed Marion Bartoli in three sets. Stosur then competed at the LA Championships as the No. 13 seed where she made it to her fifth WTA Tour final after defeating Monica Niculescu, Maria Kirilenko, Ana Ivanovic and Zheng Jie. She lost the final to tenth seed Flavia Pennetta. At her next tournament in Toronto, she defeated Heidi El Tabakh, sixth seed Kuznetsova and Virginie Razzano before being eliminated by fourth seed and eventual champion Elena Dementieva in the quarterfinals in three sets. At the same tournament, Stosur and Stubbs defeated Black and Huber in the semifinals but lost to Nuria Llagostera Vives and María José Martínez Sánchez in the final. With these results, Stosur improved her ranking to a career-high No. 15 in singles just in time for the US Open, where she was seeded accordingly. She opened with a three-set win over Ai Sugiyama before losing to American wildcard Vania King in the second round. Stosur entered the doubles event with compatriot Stubbs. As the third seeds, they made the semifinals without dropping a set, where they faced first seeds Black and Huber. They won the first set, but lost the next two after a two-day rain interruption. At the Pan Pacific Open, Stosur won her opening round over Alexa Glatch but was defeated by Maria Sharapova in the second round with Sharapova dropping just one game. Seeded 15th at the China Open, Stosur lost a three-setter to Alizé Cornet. Stosur then played in Osaka as the third seed. Stosur reached final after defeating Alexandra Panova, Akiko Morigami, Jill Craybas and Wozniacki. Stosur captured her first-ever WTA title by beating Francesca Schiavone in the final in just over an hour. This win secured her a spot at the Tournament of Champions held in Bali. She also qualified for the doubles event, partnering compatriot Stubbs. They lost a hard-fought