Hong Kong tennis star Coleman Wong advanced on Monday to the men's singles quarter-finals of the National Games.

He defeated Guangdong's Zeng Yaojie 6-2, 6-4, in Hengqin, serving up six aces in the process while taking advantage of five double faults by his opponent.

Wong said fatigue was taking a toll on him, but noted other players who are still in the competition are facing the same problem.

"I think [my condition] is getting better and better," he insists.

"It was a bit tiring on Monday because I played in both the singles and doubles yesterday, and one of the matches ended late. But it's okay. I will keep going."

Wong is hitting the courts again on Monday afternoon with doubles partner Kevin Wong, when they face Jiangsu's Tang Sheng and Sun Qian in the quarter-finals.

The singles quarter-final matches are due to start at 10am on Tuesday.