Giant-killing wildcard Samantha Stosur became the first Australian in history to reach the semi finals of the WTA Tour's Uncle Tobys Hardcourts with her victory over Spain's Magui Serna.

Building confidence and expectations with every appearance, the 19-year-old Gold Coaster, ranked 163 in the world, unsettled the seasoned No.7 seed to advance 7-6 (7-1) 7-5.

Stosur's biggest test comes when she meets No.1 seed Ai Sugiyama to compete for a place in Saturday's final.

"I don't know if it can get much better than this," laughed Stosur, punching the air after the quarter-final.

"Hopefully tomorrow I can get another one."

Stosur's third straight win made her the best-performed Australian in the history of the event.

She will do well to overcome World No.10 Sugiyama who was pushed hard in her 4-6 7-6 (7-4) 6-3 quarter-final win over Bulgarian Magdalena Maleeva.

Stosur said she needed to keep level-headed because there was still plenty of work ahead.

"I am excited but I can't get too over the top at the moment," she said.

"Hopefully this is the start of something."

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