Melbourne, Australia, 16 January 2013 | AAP

A brutally honest Samantha Stosur confessed to a mental meltdown after suffering yet more Australian Open heartache at Melbourne Park.

In a dramatic and devastating collapse, Stosur capitulated from 5-2 up in the deciding set to crash out of the Open with a 6-4 1-6 7-5 loss to China’s former semifinalist Zheng Jie on Wednesday.

The shattering defeat continued Stosur’s nightmare run at her home Grand Slam, the 2011 US Open champion having never ventured beyond the fourth round in 11 visits to Melbourne.

After battling back from a set down to seize control of the second-round contest, Stosur ultimately fell on her sword with her ninth double fault after two hours and 42 tension-filled minutes.

“At 5-2 up in the third, [with a] double break, probably is a bit of a choke, yeah,” Stosur said.

Stosur readily admitted to freezing under the weight of home pressure in her first-round loss last year to Sorana Cirstea, but felt she was managing her nerves better this summer.

Alas, the 28-year-old conceded her latest collapse was “100 per cent” mental.

“I got tight and then you start missing some balls,” she said.

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

Stosur said “crazy things” first started popping into her head when she failed to serve out the match on her first chance at 5-2.

From there, the 28-year-old was unable to recover as Zheng for the second time in a week fought back to defeat the Australian in three sets.

“It’s a pretty hard one to take when you get yourself well and truly into a winning position,” Stosur said.

“I was playing really quite well. Then all of a sudden you get to 5-2 and you lose five games straight.

“Now, unfortunately, the summer is over as quickly as what it started again.

“I’ll do what I always do and keep playing and keep trying hard. I mean, I know I’m going to get over it. It’s just you want it now, not tomorrow.”

Zheng, also a former Wimbledon semifinalist, said Stosur was playing much better than in their Sydney clash last Monday.

But the world No.40 knew she could beat Stosur if she stayed with her.

“Her kick serve and the big forehand, also backhand slice gave me the big trouble,” Zheng said.

“But today I try to play more aggressive. I try to go to the net, give her some pressure.

“This is what my coaches tell me – give her some pressure – and this way is the key to win this match.”

Despite reigning supreme in New York 16 months ago and reaching a French Open final and three semis in Paris, Stosur has faltered in the early rounds nine times in Melbourne.

Bernard Tomic, who plays German qualifier Daniel Brands on Thursday for a likely shot at Roger Federer, and fellow 20-year-old James Duckworth, up against world No.93 Blaz Kavcic, are the last Australians standing this year.