Top seed Ana Ivanovic tumbled out off the Pattaya Open on Thursday, losing in the first round to Japan's Ayumi Morita, while defending champion Daniela Hantuchova eased into round two.
Ivanovic, who has struggled to regain the form that saw her crowned world number one in 2008, lost in three sets (6-3, 5-7, 6-3) to Morita - ranked 47 places below her.
Their first round game was played over three days due to heavy rain which has dogged play on the hard surface in Pattaya and again made the court unplayable for periods of the morning.
Tournament late-entry Hantuchova survived a second set scare from rank outsider Olga Puchkova and eventually won 6-1, 3-6, 6-0.
In the final first round match, seventh seed Elena Vesnina beat Greek challenger Eleni Daniilidou 6-2, 5-7, 6-2.
They join Russian second seed Maria Kirilenko, Romanian Sorana Cirstea and Japan's Kimiko Date-Krumm in the second round.