the mixed doubles event as first seeds with Nenad Zimonjić. They received a bye in the first round, and in the second round, they defeated Colin Fleming and Sarah Borwell. They then faced the Belgium duo Xavier Malisse and Clijsters, but lost in two sets. Stosur's next scheduled tournament was the Stanford Classicn, where she was the top-seed, but lost in a semifinal match-up with Victoria Azarenka. She then participated in the San Diego Open. As the second seed, she lost in the quarterfinals to Pennetta. Due to a shoulder injury, she withdrew from the Cincinnati Open and the Rogers Cup in Montreal. This meant that Stosur had only taken part in one of the five Premier-5 tournaments of the year. After taking time off to recover from her injury, she took part in the Pilot Pen Tennis tournament at New Haven, in hopes of regaining some of the lost ranking points and in preparation for the US Open. Stosur lost to Petrova in the quarterfinals. At the US Open, Stosur was seeded fifth. In her first US Open quarterfinal, she was up a break in the third set, before falling to defending champion and second seed Clijsters in three sets. Stosur announced that she would not take part in the 2010 Commonwealth Games. Instead, she competed at the final Premier Mandatory event of the year, the China Open, where she lost in the first round to qualifier Anastasija Sevastova in three sets. Stosur qualified in singles for the year-ending WTA Championships in Doha for the first time in her career, following the withdrawal of Venus Williams. Stosur then attempted to defend her title at the Japan Open as the top-seed, her only International tournament of the year. She lost against Kimiko Date-Krumm in the quarterfinals in a final-set tie-break, becoming the first top-ten player in WTA history to lose to an opponent over the age of 40. Stosur competed at the WTA Championships, where she was seeded fifth. Stosur was drawn in the Maroon Group alongside world No. 1, Caroline Wozniacki, world No. 6, Francesca Schiavone, and world No. 9, Elena Dementieva, seeded first, fourth and seventh, respectively, due to the Williams sisters' withdrawal. In her first match against Schiavone, she avenged her Roland Garros final loss to the Italian by defeating her in straight sets, coming back from a 0–4 deficit in the first set. Her next opponent