Michael Cheng Chun-leung's bid for a gold medal on his Asian Championships debut suffered a setback on Saturday with a sudden loss of form.
The 19-year-old had his worst of three days of racing off Stanley, finishing fourth, third and second in his three RSX races.
Although Cheng still leads with 14 penalty points after eight races, compatriot Andy Leung Ho-tsun surged to tie with Cheng at the top of the standings. Cho Won-woo of South Korea maintained his third place overall but is already a hefty nine penalty points behind.
Leung, Hong Kong's representative at the 2012 Olympic Games, came back strongly with two wins and a seventh place.
"I did not sleep well last night and when I woke this morning, I knew I wasn't at my best," said Cheng, who captured a silver medal for Hong Kong at the Youth Olympics in Singapore three years ago. "Perhaps I was a bit tense after being in the lead for the first two days, especially as this is my first senior Asian Championships. "I have to relax tonight and forget about the table. And when I start again, I need to avoid making mistakes."
In the women's RSX, home favourite Hayley Chan Hei-man struggled in lighter wind than the two previous days, but the London Games Olympian said the change of conditions had had little impact on her performance.