Melbourne, Jan 25: Leander Paes and his Czech partner Radek Stepanek advanced to the men's doubles semi-finals at the Australian Open here Wednesday while Sania Mirza and her Russian partner Elena Vesnina missed a great opportunity to make the women's doubles final.

Sania and Vesnina lost both the first and third sets after being in a commanding position against Russia's Vera Zvonareva and Svetlana Kuznetsova -- though they won the second easily. In the ultimate analysis, their 51 unforced errors proved their undoing as they went down 6-7(4-7), 6-2, 4-6. 

The Indo-Russian pair had more than one opportunity to go 5-2 up in the decider, but unforced errors cost them the match. Earlier, they squandered a chance to wrap up the first set also. 

Paes and Stepanek carried on their good form as they strolled to another straight-set victory, this time against the American-Brazilian pair of Eric Butorac and Bruno Soares 6-4, 7-6(7-4).

The Indo-Czech pair will play second seeds Max Mirnyi of Belarus and Canadian Daniel Nestor in the semi-finals.

India's Mahesh Bhupathi and Rohan Bopanna crashed out in the pre-quarterfinals Sunday.