Australian Casey Dellacqua was bundled out of the $US170,000 ($A190,000) Pattaya Women's Open with a shock 7-5 2-6 6-2 loss to Slovenian Andreja Klepac.

Klepac, ranked just 145 in the world, played an aggressive baseline game to overwhelm second seed Dellacqua in one hour and 49 minutes.

"I'm happy with this win. I played good tennis but the second set I made a few mistakes and didn't serve well," Klepac, 21, said.

"I concentrated again and served better in the third."

Top-seeded Agnieszka Radwanska advanced to the quarter finals with a 6-2 6-2 victory over former champion Anne Kremer.

The 18-year-old Pole, a quarter-finalist in January's Australian Open who is ranked world No.21, delivered a mix of drop shots, lobs and spins to beat the tournament's 2000 winner in one hour, 23 minutes.

In another second round upset, Russian qualifier Vesna Manasieva chalked up a 6-2 6-1 win over third seed Angelique Kerber of Germany in just 74 minutes.

Fourth-seeded Chan Yung-jan of Taiwan also advanced to the third round by beating Lilia Osterloh of the US 6-4 6-2.

Ekaterina Bychkova of Russia's 6-4, 6-4 victory over India's Sunitha Rao set her up for a quarterfinal match against Manasieva, while Thailand's Tamarine Tanasugarn was headed for a third round match against Radwanska after defeating Russia's Olga Poutchkova 4-6, 6-4, 6-4.

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