SAMANTHA Stosur admitted she might have "choked" after another shattering loss at the Australian Open yesterday.

Her latest loss, this time to Chinese world no. 40 Jie Zheng on Rod Laver Arena 6-4, 1-6, 7-5, continued her horror run at her home tournament, the 2011 US Open champion having never gone beyond round four in 11 attempts at Melbourne Park.

Ninth seed Stosur looked to have the match firmly in her grasp after fighting back from only to lose her serve twice after being 5-2 up in the final set to allow Zheng, who beat Stosur in Sydney last week, to fight back and take the match.

Poignantly the Aussie's ninth double fault sealed the win for her Chinese opponent.

The odds were stacked against Stosur when she dropped the opening set after 54 minutes.

The Queenslander had won only six grand slam matches from 37 tries after losing the first set and also fell victim to Zheng last week in Sydney.

Stosur said she was obviously disappointed to have lost the game, especially after dominating the second and most of the final sets.

"Obviously it's a pretty hard one to take when you get yourself well and truly into a winning position playing really quite well," she said.

"Then all of a sudden you get to 52 and you lose five games straight."

Stosur said she had plenty going through her mind at 5-2 up in the final set but she knew what she wanted to do but just could not execute it.

"Oh, I think it's 100% (a mental thing)," she said.

"I think, yeah, that's what it was. I got tight and then you start missing some balls.

"You probably think a little bit too much. You do it over and over and over again, and then, yeah, you start not wanting to miss rather than wanting to make the winner.

"Instead, it's I don't want to make the error."

Asked if she choked, Stosur said: "I don't know. Whatever word you want to put on it. At 52 up in the third, double break probably is a bit of a choke, yeah."