Top seed Vera Zvonareva made smooth progress at the Pattaya Open but Dominika Cibulkova made a shock exit.

Russian Zvonareva beat Thai qualifier Varatchaya Wongteanchai 6-2 7-5 but second seed Cibulkova was thrashed 6-4 6-1 by Britain's Anne Keothavong.

Keothavong said on Twitter: "I think we were both a little under-cooked having only arrived in Pattaya yesterday [Monday] but I was able to adjust better and I'm really pleased."

But her fellow Federation Cup heroines Heather Watson and Laura Robson were brought back down to earth by first round defeats.

Like Keothavong, they were part of the Great Britain squad which won all four of their Fed Cup ties in Israel to book a promotion play-off.

Watson is yet to win a WTA match this season, having also gone out in the first round in Hobart and the Australian Open.

She was beaten in straight sets by American Vania King, a solitary break enough to give world No 59 King the first set and two more in the second saw her emerge a 6-4 6-2 victor in one hour and 30 minutes.

Robson was 5-2 down to Uzbekistan's Akgul Amanmuradova when she had to withdraw with an apparent back strain.

Third seed Daniela Hantuchova dropped just two games in beating home hope Nungnadda Wannasuk but fifth seed Jie Zheng and sixth seed Galina Voskoboeva also made early exits.

Zheng was defeated 6-3 6-2 by qualifier Su-Wei Hsieh and Voskoboeva was trailing 6-3 4-2 to experienced Thai player Tamarine Tanasugarn when she was forced to retire.

Sania Mirza required three sets to see off Ayumi Morita while 41-year-old Kimiko Date-Krumm defeated Nicha Lertpitaksinchai 6-1 6-1.

Fourth-seeded Russian Maria Kirilenko battled from a set down to overcome Australia's Casey Dellacqua 4-6 7-6 (8/6) 6-3 to set up a second-round meeting with Australia's Anastasia Rodionova - a 6-4 6-0 winner against Iryna Bremond of France.