Pattaya, Thailand - Fourth seed Sorana Cirstea joined British No 1 Heather Watson and Japan's Kimiko Date-Krumm 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 No 13 Ana Ivanovic who trailed 1-2 in the final set against Ayumi Morita before rain suspended play late on 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.
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 a 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 Date-Krumm was pushed hard on her way to a 7-5 first set win against South Africa's Chanelle Scheepers who ranks 13 places higher at 64, before the 28-year-old Shceepers capitulated in the second set 6-1.
She will face former world No 1 Ivanovic if the Serb - who arrived in Thailand looking to build on a decent showing in Melbourne - progresses to the second round.
Results from the second day of the WTA Pattaya Open on Tuesday:
First round singles
Sabine Lisicki (GER) bt Tatjana Malek (GER) 6-2, 6-3
Anastasija Sevastova (LAT) bt Misaki Doi (JPN) 6-4, 6-2
Sorana Cirstea (ROM) bt Bethanie Mattek-Sands (USA) 6-1, 6-3
Maria Kirilenko (RUS) bt Akgul Amanmuradova (UZB) 6-3, 7-5
Anastasia Rodionova (AUS) bt Vania King (USA) 6-4, 6-4
Heather Watson (GBR) bt Timea Babos (HUN) by retirement 6-1, 3-0
Luksika Kumkhum (THA) bt Casey Dellacqua (AUS) 6-2, 6-2
Kimiko Date-Krumm (JPN) bt Chanelle Scheepers (RSA) 7-5, 6-1
Nina Bratchikova (RUS) bt Shahar Peer (ISR) 6-3, 6-3
Ana Ivanovic (SRB) vs Ayumi Morita (JPN) match suspended at 3-6, 7-5, 1-2
Still to play:
Daniela Hantuchova (SVK) vs Olga Puchkova (RUS)
Elena Vesnina (RUS) vs Eleni Daniilidou (GRE)