Local hopes Boonsak Ponsana and Ratchanok Intanon are on course to win the titles at the SCG Thailand Open with both booking semi-final places last night.
Top-seeded Boonsak Ponsana during his 2-1 win over Rajiv Ouseph.
In the quarter-finals, men's top seed Boonsak beat England's Rajiv Ouseph 21-15, 21-23, 21-12 while women's second seed Ratchanok beat compatriot Nichaon Jindapon 21-16, 21-18.
World No.7 Boonsak needed 62 minutes to finish off Ouseph in the US$120,000 event at Nimibutr Gymnasium.
Having claimed the first set, the 31-year-old should have easily won the match when he led 20-14 in the second set. But the sixth-seeded Englishman fought back spiritedly to win 23-21. However, Boonsak, who won the 2004 Thailand Open, regrouped to win the deciding set 21-12.
Boonsak said he hopes to win his second Thailand Open crown to boost his confidence before contesting next week's US$650,000 Indonesia Open and the US$200,000 Singapore Open the following week.
In the semi-finals, Boonsak will meet world No.60 Wisnu Yuli Prasetyo of Indonesia, who defeated HS Prannoy of India 21-12, 21-19.
Thai teenager Sitthikom Thammasin continued his impressive run with a 21-17, 21-12 win over Taiwan's Hsu Jen-hao in the quarter-finals. The 17-year-old Thai, who beat second seed Tommy Sugiarto in the first round, had few problems against the world No.33.
Sitthikom will next meet K Srikanth of India in the last four after the 13th seed beat Son Wan Ho of South Korea 21-17, 21-18 in the quarter-finals.
In the women's singles, Ratchanok will meet Hsiao Ma Pai, the fourth seed, for a place in the final after the fourth seed fought back for a 2-1 win over fifth seed Sapsiree Taerattanachai.
World No.5 Ratchanok is 2-0 against world No.19 Hsiao with the Thai winning 21-14, 21-16 in their recent meeting at the Swiss Open in March.
Ratchanok's path to her maiden triumph at her national Open looks smoother after top seed and world No.2 Saina Nehwal suffered a shock loss in the quarter-finals.
Nehwal, who beat Ratchanok in last year's final, won the first set 21-13 against Gu Juan but the 23-year-old Singaporean took the next two sets 21-12, 21-18.
Ranked 23rd in the world, Chinese-born Gu will face Thailand's Busanan Ongbumrungpan, who saw off compatriot and third seed Porntip Buranaprasertsuk 21-14, 17-21, 21-17.
Gu is 1-2 against world No.22 Busanan with Gu winning in the semi-finals in Malaysia last month.
In the women's doubles, top seeds Duanganong Arookesorn and Kunchala Voravichitchakul lost to eighth seeds Nitya Maheswari and Grysia Polii of Indonesia 21-17, 21-13 in the quarter-finals.
Reigning champions Saralee Thoungthongkam and Narissapat Lam were defeated by Thailand's Puttita Supajirakul and Sapsiree in the second round on Thursday.
Today's semi-finals begin at 11am and the tournament ends tomorrow.