The Thai failed to maintain the form she displayed throughout the week, defeating American rising stars Christina McHale in the first round and Madison Keys in the quarter-finals.
“I played very bad today. It was not because I was excited about reaching my first WTA semi-finals. I was totally off for no reasons,” said Luksika, the world No 93, with disappointment writ large on her face.
In the first set, Luksika made several errors in the sixth game and lost her serve when she hit a forehand long to fall 4-2 behind. At 2-5 Luksika was still rusty as she made error after error before losing the set in 23 minutes.
In the second set, Luksika sprayed two successive backhands wide to lose serve in the fourth game and fell 3-1 behind. After a talk with coach Subin Sricha-aen during the changeover, Luksika avoided going for the lines and kept the ball in play. That proved effective. She broke back for 3-4 with a razor-sharp service return winner.
However, it was the world No 37 Diyas who raised the level of her game when it mattered most. She set up the match-point with a forehand winner and wrapped up the 67-minute match when Luksika’s forehand sailed wide off the line.
It was Luksika’s first defeat to the Kazakh whom she had beaten twice in Gaungzhou and Paris last year. The Thai will play her next event in Ningbo at the end of the month.
Meanwhile, former US Open winner Samantha Stosur beat Ukraine’s Elina Svitolina to reach the final.
The top-seeded Australian downed third seed Svitolina 7-6 (8/6) 6-2 to set up a final against Diyas.