Tamarine, who skipped the recent SEA Games to focus on personal goals, cruised to a 6-2 6-2 victory against Kseina Lykina of Russia.
Nudnida was forced to work a little harder, saving two set points in a first set tie-break before prevailing against Japanese seventh seed Kurumi Nara 7-6 (10-8) 6-2. The win set up her fourth Challenger quarter-final this year. Nudnida next faces top seed Kimiko Date-Krumm of Japan, while Tammy takes on second seed Japanese Misaki Doi.
Adding salt to his wounds after losing in Sunday’s SEA Games singles final, Danai Udomchoke went down 7-6 (8-6) 7-6 (10-8) in the first round to Japan’s Takao Suzuki.