Sania Mirza beat Tamarine Tanasugarn of Thailand to advance to the semi-finals of the singles event of the Pattaya Open.

Sania had to toil hard for one hour and 44 minutes to emerge 7-5 6-4 victorious over her sixth seeded opponent in the quarterfinal match of the USD 220,000 event.

She will next meet eighth seed Magdalena Rybarikova of Slovakia who also registered an upset 6-4 6-1 victory over second seed Caroline Wozniacki of Denmarkij in another quarterfinal match.

Sania seized early initiatives in the match, breaking the world number 41 Tanasugarn in the sixth game of the opening set to lead 4-2.

But the lead was shortlived as the Thai girl broke back the Indian in her very next serve and pocketed three games in a row to move to 5-4.

The 22-year-old Hyderabadi, whose ranking plummeted to 126 as she was out of action for most part of 2008 due to wrist injury, however, stepped up the gas and broke her opponent in the 11th game and then held her serve to pocket the first set 7-5.

The second set went on similar lines with Sania converting two break points out of three while Tanasugarn could manage only one.

Partnering Italian Mara Santangelo, Sania had already made it to the semi-finals of the doubles event. They will face Yanasugarn and Yaroslava Shvedova of Kazakhstan.