In a closely fought encounter, No.6 seed Cepelova held her nerve during a tense conclusion to close out a 6-4, 2-6, 6-4 victory in a fraction over two hours.
Exactly two years ago, Peng produced some of the best tennis of her career to reach the semifinals of the US Open. However, since then success has been thin on the ground after a debilitating back problem forced her to miss nearly all of 2015.
Progress since her return has been slow, struggling for wins away from the ITF Circuit. Against Cepelova she had her chances, threatening to get edge ahead in the deciding set only to surrender the solitary break in the seventh game.
Elsewhere, there were wins for Cepelova's fellow seeds, Wang Qiang, Duan Ying-Ying and Tamira Paszek. Top seed Wang withstood a late rally to defeat Nigina Abduraimova, 6-4, 7-6(4), while Duan, the No.3 seed, provided further home cheer with a 6-3, 7-5 victory over Sara Sorribes Tormo.
No.4 seed Paszek was pushed even harder, but finished strongly to see off You Xiaodi, 7-5, 5-7, 6-1.