Hong Kong's mixed medley relay swimmers advanced on Thursday to the final at the National Games.

The 4x100m team of Cindy Cheung, Nicholas Cheung, Ralph Koo and Li Sum-yiu clocked a little more than three minutes 54 seconds – good for sixth overall.

They'll compete again at around 8.40pm in Shenzhen.

Li said coaches only told them about the four of them being chosen for the race on Wednesday night, and she was overjoyed with the results.

She told RTHK that it wasn't easy swimming in the lane next to double gold medallist at the Paris Olympics, Zhejiang's Pan Zhanle.

"I was right next to Pan. When I got into the pool, I could feel that his waves were rushing towards my side. I tried very hard to follow the waves, but unfortunately they kind of swept me aside," Li said.

"It's really difficult. But hopefully later on we'll be swimming near people at similar levels that we're at - then we might be quicker."

In the women's 200m butterfly heats, Kassy Yeung also advanced to the semi-finals due on Thursday night ranked 10th overall, finishing with a time of two minutes and 12.79 seconds.

Teammate Mya Mathis, however, didn't make the cut.

In her individual 50m backstroke, Cindy Cheung was unable to advance from the heats, as her time of 29.6 seconds was only 22nd overall. Teammate Ashley Chan, meanwhile, was 25th overall.

Ian Ho and Nathan Chan were also out following the men's 100m freestyle heats.