Samantha Stosur came crashing back to earth with a shattering second-round exit from the Australian Open on Thursday night.

A year after her grand slam-best run to the last 16 at Melbourne Park, Stosur succumbed 6-4 2-6 6-2 to unseeded Jelena Kostanic, a Croatian ranked 40 places below the Australian No.1 at 67th in the world.

Stosur had momentum on her side after peeling off six straight games to recover from 2-0 down in the second set to level the match at one set apiece, only to capitulate with a flurry of unforced errors.

The 22-year-old Queenslander had been seeded at a major for the first time and was hoping to at least match her 2006 Open performance, if not qualify for a maiden grand slam quarter-final appearance.

Alas, Stosur must rebound from one of her most disappointing defeats and steel herself for another doubles assault.

The winners of the 2006 French Open and 2005 US Open doubles titles, Stosur and American partner Lisa Raymond are the top seeds in the women's doubles in Melbourne for the second year in a row.

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