Pattaya, Thailand, 30 January 2013 | AAP

Fourth seed Sorana Cirstea joined British number one Heather Watson and Australia’s Anastasia Rodionova in the second round of the Pattaya Open as the trio cruised through their matches on Tuesday.

But it was heavy work for the top seed and world number 13 Ana Ivanovic who trailed 1-2 in the final set against Ayumi Morita before rain suspended play late Tuesday.

She will be hoping to regroup to join second seeded Maria Kirilenko in the next round, who made it through with a nervy 6-3 7-5 win over unfancied Uzbek Akgul Amanmuradova.

Australia’s Anastasia Rodionova also advanced after beating Vania King 6-4 6-4, however, Casey Dellacqua was knocked out by Thailand’s Luksika Kumkhum 6-2 6-2.

Rain prevented last year’s champion Daniela Hantuchova, a late entry due to a withdrawal, from starting her title defence against Russian Olga Puchkova.

Before the skies opened Romanian ace Cirstea completed a routine 6-1 6-3 win over American challenger Bethanie Mattek-Sands behind a strong-service game.

Fresh from climbing to a career-high world ranking of 40 after an impressive showing in the Australian Open, Heather Watson swept to a 6-1 3-0 lead when Hungarian Timea Babos retired through injury.

Forty-two-year-old Kimiko Date-Krumm of Japan was pushed hard on her way to a 7-5 first set win against South African Chanelle Scheepers who ranks 13 places higher at 64, before the younger woman capitulated in the second set 6-1.

She will face former world number one Ivanovic if the Serb – who arrived in Thailand looking to build on a decent showing in Melbourne – progresses to the second round.