The top seed won an all-Thai encounter with Thassha Vitayaviroj to reach the semi-finals of the US$10,000 PTT Bangkok Open ITF Women's Circuit 3 yesterday.

Nudnida was two points away from losing the second set at 30-30 and 3-5, but dug deep to turn the situation around and beat her countrywoman 6-4 7-6 (7-5) in the quarter-finals at the Tennis Academy of Asia.

It was the third consecutive time that Nudnida had stamped her authority over the fifth-seeded Thassha, a Fed Cup team-mate. Her previous wins came in the University Games last December and the National Championships earlier this year.

"I had a good start but was in a rush to finish off and made some silly errors. I had to refocus and played one point at a time to pull it off," said the 19-year-old from Sukhothai.

Ranked 408th in the world, Nudnida was in top gear, attacking her rival with powerful ground strokes to break twice and take a 4-0 lead. She went 5-2 up but a brief bout of nerves cost her two games as Thassha narrowed the deficit to 4-5.

In the 10th game, which featured long baseline rallies, Nudnida made fewer errors than her opponent and managed to take a crucial break to wrap up the opening set.

Hasty play saw Nudnida drop serves and trail 5-3 in the second set. But she gritted her teeth and chased down every rally to escape from 30-all in the eighth game to break back. Both then held their serves to force the tie-break, which Nudnida won in a canter as her opponent made many unforced errors.

"She was more consistent in the second set. I had to be very patient to earn each point," added the Thai, who is determined to achieve her best result in the Bangkok Open series. She reached the quarter-finals in the first week and the semi-final last week.

"I think I'm playing better this week and if I can keep up with the good work, I stand a chance of winning the title," said Nudnida, who will next play Lee Jin-a of South Korea, a 6-2 6-0 winner over Varatchaya Wongteanchai.

In the other quarter-finals, Hong Kong's ChanWing-yau Venise beat Dilyara Saidhodjaeva of Uzbekistan 6-0 7-5, and Selma Andradeb of the Netherlands picked off China's Lu Xi 6-3 6-4.

Lerpong Amsa-ngiam

The Nation