Lee first to reach semis at Badminton Superseries Finals
Lee Chong Wei celebrates after winning the men's singles final at the Hong Kong Open on November 24, 2013
The Malaysian ace booked his place in the final four after a swift 21-6, 21-8 victory in 29 minutes, bringing him a step closer to a historic fourth title.
It was his second straight victory in the round-robin group stage following his 21-10, 21-18 win over China's Wang Zhengming on Wednesday.
"I'm glad to have won quite comfortably today. I prepared myself well and I now get to shift my focus to tomorrow's match," said Lee, who was exceptionally deadly with his smashes and drop shots against Boonsak.
The three-time champion, who faces Jan O Jorgensen tomorrow in his final Group A match, said the Dane's confidence will be sky high after winning the French Open.
"Jorgensen is an attacking player, so I must be strong in my defence. I must not underestimate my opponent," said the 31-year-old Malaysian.
It was a fruitful day for the Japanese squad as second-seeded Kenichi Tago edged another step closer to the semi-finals after beating Indonesia's Sony Dwi Kuncoro 12-21, 21-19, 21-17 in Group B.
Men's pair Hiroyuki Endo and Kenichi Hayakawa also scored an upset win over three-time champions Mathias Boe and Carsten Mogensen of Denmark 21-18, 21-15.
Misaki Matsutomo and Ayaka Takashi then beat Pia Zebadiah Bernadeth and Rizki Amelia Pradipta of Indonesia 21-11, 18-21, 21-15 in a Group A women's doubles tie.
The only bad news for Japan was that their second men's pair, Hirokatsu Hashimoto and Noriyasu Hirata, had to pull out of the tournament after Hirata suffered a leg injury.
The $500,000 showcase event brings together the top eight performers in each of the five categories based on points earned from the 12 Superseries tournaments.
The top two from groups A and B will play in crossover semi-finals on Saturday.