The Thai qualifier looked like she might pull off another upset, after winning the first set in a tie-break against fourth seed and world No 55 Ayumi Moriyta. But the Japanese took advantage of a right-leg injury that hampered Luksika’s mobility and hit back for a 6-7 (7-9) 6-4 6-1 victory in two hours of gruelling baseline rallies.
Morita set up a semi-final against Karolina Pliskova.
Playing with her right leg taped, Luksika, only the second Thai to reach the last eight of a WTA event after Tamarine Tanasugarn, fought back from 2-5 down in the second set and was about to serve at 4-5 to level things when she called for treatment. The medical intervention seemed to have little effect, as she was broken easily in the following game.
Luksika later made amends in the doubles quarter-finals, teaming up with Erika Sema of Japan to beat fourth-seeded Rika Fujiwara of Japan and Saisai Zheng of China 5-7 6-3 16-14.