Samantha Stosur continues her ominous pre-US Open form at Cincinnati Masters Samantha Stosur of Australia returns a shot to Jamie Hampton during the Western & Southern Open on August 14, 2013 at Lindner Family Tennis Center in Cincinnati, Ohio. SAMANTHA Stosur has continued her promising US Open lead-up form and edged closer to a quarter-final showdown with Serena Williams at the Cincinnati Masters. Stosur advanced to the third round on Wednesday with an impressive 6-3 7-6 (7-3) victory over world No.26 Jamie Hampton, the Australian's ninth win from her past 10 matches. The 11th seed next faces Romanian Simona Halep, who upset eighth-seeded Wimbledon champion Marion Bartoli 3-6 6-4 6-1. Victory over Halep would likely thrust Stosur into a last-eight blockbuster against Williams, the world No.1 she upstaged in the 2011 US Open final to land her maiden grand slam title. Williams overcame early jitters to defeat Canada's Eugenie Bouchard 4-6 6-2 6-2 in her second-round match. The American said she produced the worst shot she could ever remember at one stage in the one-hour, 47-minute match. "I even had an easy approach shot and it went not slightly wide, it was like 50 feet out," Williams said. That was actually embarrassing. I thought I'd never hit a shot like that professionally. After a first-round bye, it was Williams' first match since securing her eighth title of the year in Toronto last week. Stosur won the title the previous week in Carlsbad, California in a promising sign ahead of the US Open starting in New York on August 26.