Top seed Lee, aiming for a fifth consecutive title at the event, saw off India’s Ajay Jayaram after 36 minutes of their quarter-final with a 21-16, 21-16 win.

It took the same amount of time for unseeded Zainuddin to overcome Hong Kong’s Angus Ng Ka Long, beating the eighth seed 21-11, 21-15.

"He has the pace to face higher seeded players," said Morten Frost, technical director of the Badminton Association of Malaysia, about Zainuddin.

"I am not surprised with his good performance here; he has raised his game to a level he should be at.

"Iskandar has the pace to follow the top players.

"I also expect him to be in the top 25 and I am not surprised with what he has dished out so far, beating seeded players in the tournament."

Lee will face Indonesia's Tommy Sugiarto in the semi-finals, while Zainuddin will take on India's Srikanth Kidambi.

Third seed Sugiarto defeated China's Qiao Bin 21-6, 21-17, and second seed Kidambi beat another Chinese Huang Yuxiang 21-15, 21-14.

In the women’s singles draw, India’s Pusarla Venkata Sindhu overcame Indonesia’s Lindaweni Fanetri to set up a semi-final clash with South Korean number one seed Sung Ji-hyun, who came from behind to defeat Japan’s Sayaka Sato 13-21, 21-18, 21-11.

The other semi-final pits Sato’s compatriot Yui Hashimoto, a 13-21, 21-18, 21-11 winner at the expense of South Korea’s Bae Yeon-ju, against Scotland’s Kirsty Gilmour, who eliminated Thailand’s Busanan Ongbumrungpan with a 21-19, 21-10 victory.

The semi-finals are scheduled to take place tomorrow, followed by the finals on Sunday (January 24).