Samantha Stosur is officially the new queen of Australian tennis following her surge to the fourth round of the Australian Open.

Stosur will leapfrog Alicia Molik to become the country's new No.1 when the updated WTA rankings are released on Monday.

The 21-year-old Queenslander will rise from her current position of No.98 in the world to inside the top 70, while Molik - out indefinitely with a career-threatening inner ear condition - will tumble as low as 90th after being unable to defend the rankings points acquired from reaching last year's Open quarter-finals.

Stosur put the disappointment of her loss to Martina Hingis behind her to continue her twin assault on doubles titles at Melbourne Park on Tuesday.

Stosur and American Lisa Raymond are the top seeds in the women's doubles and cruised into the semi-finals with a 6-3 6-2 win over 10th seeds Gisela Dulko and Maria Kirilenko.

The US Open champions will next face fifth seeds Anna-Lena Groenefeld and Meghann Shaughnessy for a berth in their second straight grand slam final together.

Stosur then teamed up with Melbourne's Paul Hanley to post a 6-4 6-3 second-round mixed doubles win over Bryanne Stewart and Jim Thomas.

The fifth seeds will play fourth-seeded Americans Mike Bryan and Corina Morariu in the quarter-finals as Stosur attempts to defend the title she won last year with fellow Queenslander Scott Draper.

Stosur said she had no regrets after pushing Hingis to a second-set tiebreaker before succumbing 6-1 7-6 (10-8) to the former world No.1 in the biggest match of her life on Monday night.

"I'm just glad with the way I fought out there and got myself back into the match and had a chance at winning that second set," Stosur said.

"That's just really what I'm going to take out of it - how I competed out there and just did whatever I could.

"She's just an unbelievable player. She hasn't got a huge serve, she hasn't got big groundies, but she's got everything mentally and just anticipates really well.

"She just knows what's going on out there. She can hit lob winners on the line and reflex volleys back when she needs to.

"She's just an awesome player. Now playing her, I know why she's won all these grand slams and why she's probably going to go down as one of the greats ever."

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