Chong Wei was in great form beating world No. 7 Wang Zhengming of China 21-10, 21-15 in the third round.
Long had a comfortable win over countryman Hsu Jen-hao winning 21-16, 21-2.
In head-to-head encounters Long holds a slender 10-9 record against Chong Wei.
In other men's singles matches Denmark's No. 2 seed Jan O Jorgensen beat Thailand's Boonsak Ponsana 21-10, 21-10 and will face Taiwan's Chou Tien Chen in the quarter-finals.
Fourth seeded Lin Dan of China comfortably reached the quarter-finals beating Taiwan's Chia Hung Lu 21-16, 21-15, where he faces Ginting Anthony of Indonesia next.
South Korea's Kwang Hee Heo will face Hong Kong 11th seed Wei Nan next on Friday after beating Ihsan Maulana Mustofa of Indonesia 20-22, 21-19, 21-18.