Top-ranked Tai Tzu-ying pushed through a challenging second set to clinch a 21-8, 23-21 victory against Denmark's Mia Blichfeldt and move into the finals of badminton's Thailand Open. The Taiwanese player made a strong start, but Blichfeldt's strong defence caused her problems. "In the second game, the speed of the shuttle was different down that end and I had to adapt to that," said Tai.
She said she would need to bring her A-game on Sunday when she faces Spain's Carolina Marin, a former world number one, in the final.
Earlier in the day, the Spaniard trounced South Korean teenager An Se-young 21-16, 21-16.
"I didn't feel any negative situation for myself, and I think if I play like this, I'm so ready for tomorrow," she said
Meanwhile, seven-seeded Angus Long of Hong Kong started off slow against Taiwan's Chou Tien-chen, ranked second in the world in men's singles, but won in a 17-21, 21-18, 21-15 upset.
Chou said he "lost control" by the third set. "I made some easy mistakes and that made me lose the second game. I just didn't feel in control."
Ng will go up against Denmark's Viktor Axelsen on Sunday. The fourth seed beat Indonesia's Anthony Ginting 21-19, 13-21, 21-13.
The Thailand Open is the first of three consecutive tournaments in Bangkok culminating in the World Tour Finals from January 27.
Flown in a week before the start for quarantine and testing, the players are facing off in a bio-secure "bubble", with no spectators allowed.
The tournament has been overshadowed by the positive cases for Egyptian mixed doubles player Adham Hatem Elgamal, a German coach and a French staff member.
Elgamal, who had to drop out on the first day and was moved to a hospital, took to Instagram on Saturday to raise doubts about his initial test results.
He told AFP that since arriving at the hospital, subsequent tests had shown negative results.
"They made a mistake, and I am paying for this mistake because I missed the tournament, and I am ok with this but I want to go back to Egypt," Elgamal told AFP.
"Why am I not allowed to go back if I am OK and I tested negative?"
But doctor Piyaja Nagavajara insisted Elgamal had tested positive on the PCR test, which is the highest standard.
A subsequent antibody test indicated a "recent infection" and a chest x-ray led a team of doctors to conclude that a "viral infection went to his lungs".
"I think the problem is a miscommunication or maybe we don't have an effective translator," Piyaja told AFP.