A victory over world No 1 Lin Dan on Friday clearly boosted Boonsak's confidence as he eased past Singapore's Ronald Susilo 21-13 21-15 in the semi-finals - a repeat of Susilo's defeat to the Thai at the Athens Olympics.

The remarkable Boonsak kept troubling Susilo's backhand, which caused the Singaporean to vent his frustration by throwing his racquet during the first game.

The struggling Susilo then stepped up the tempo, but could not overcome the calmness and consistency of Boonsak and conceded a series of points as a result of errors.

Trailing 15-20 in the second game, the desperate Susilo, who failed to regain his composure, returned a Boonsak smash wide, allowing the Thai to win and celebrate his triumph with his coach at the side of the court.

The victory earned Boonsak his first final in a season in which he has never previously gone beyond the quarter-finals.

The 25-year-old next faces China's Chen Yu, who downed former world No 1 Peter Gade of Denmark 21-15 23-25 21-17 in the other semi-final.

World No 11 Boonsak has lost to the sixth-ranked Chen in their two previous encounters, including the All-England Super Series in March.

In the mixed doubles, his compatriots Sudket Prapakamol and Saralee Thungthongkam also enjoyed success in the semi-finals, beating China's world No-2 pairing Xie Zhongbo and Zhang Yawen 16-21 22-20 21-18.

The splendid Sudket and Saralee next take on Indonesians Flandy Limpele and Vita Marissa, who crushed compatriots Nova Vidianto and Lilyana Natsir - the world No 1s - 21-16 16-21 21-17 in the other semi-final.

This is the first final of the season for Sudket and Saralee.

The Thai duo reached the Singapore Open final two years ago, but failed to lay their hands on the trophy, falling to China's Zhang Jun and Gao Ling.