Samanths Stosur became victim of the first major upset in 2010 China Open as the Australian fourth seed was ousted by Latvian qualifier Anastasija Sevastova on Sunday.

The world seventh ranked Stosur seemed to be on course for an easy opening victory as she closed out the first set 6-2. However, the 55th ranked Sevastova started to fight back in the second set, forcing into a thrilling tie-breaker in which the Latvian won 7-5.

The deciding third set remained close, with Stosur, finalist of the French Open this year, still could not recapture her form to stand out. The 20-year-old Sevastova capitalised on her opponent's poor first serving and seized a crucial service break near the end to seal her victory of 2-6, 7-6 (7-5), 7-5.

Stosur was not the only seeded player ousted on Sunday. French 14th seed Aravane Rezai also tasted a sour defeat after being muscled out 6-4, 2-6, 6-4 by Gisela Dulko of Argentina.