Top seed Roberta Vinci was knocked out of the first round of the Malaysian Open after losing to Taiwan's Kai-Chen Chang 5-7, 6-2, 6-1 on Tuesday. (Click here for latest Tennis stories)
The 33-year-old Italian, ranked 10th in the world and eyeing her second WTA tour title of the season, succumbed to a player with a world ranking of 153.
In an earlier first-round match, second seed Elina Svitolina of Ukraine easily dispatched Japan's Miyu Kato in straight sets, 6-1, 6-1.
China's Zhaoxuan Yang, seeded eighth, beat her fellow countrywoman Saisai Zheng 4-6, 6-3, 6-2.
On Monday Eugenie Bouchard had an easy win over Hong Kong's Zhang Ling, 6-3, 6-1 to advance to the second round.
The Canadian, who has been showing signs of returning to form, will meet Japan's Karumi Nara on Wednesday.
Third seed Sabine Lisicki from Germany also heads to the second round Wednesday, facing Barbora Krejcikova from the Czech Republic.
Lisicki had defeated Magda Linette from Poland 6-4, 7-6(5) on Monday in a tough battle in hot and humid conditions.