Stephen is the captain of Ying Wa College's basketball team who won two titles in the 2009/10 season - the Division One inter-school competition and the Panasonic Cup.
The 18-year-old Form Seven student also won two Most Valuable Player awards in the 2010 Nike All-Hong Kong Youth Basketball League, and two championship trophies with his team in the league's 3-on-3 and 5-on-5 competitions.
His younger sister Rebecki, 14, is a Form Three student at STFA Lee Shau Kee College. She is the reigning champion of the All-Hong Kong Schools Jing Ying Cross-Country Tournament.
Until last year, Stephen was a student at CNEC Christian College. He decided to move to Ying Wa after completing his HKCEE. "I felt I needed more exposure to higher-level competitions. At Ying Wa, I could play in [Division One] inter-school competitions," he says. His results have proved he made the right decision.
Rebecki often goes to watch her brother play - but he hasn't been able to return the favour.
"I usually train five or six days a week," says Stephen. "I need to attend all Hong Kong team, Hong Kong under-18, A1 Division Winling team and school team training sessions. Sometimes I am too tired to go and watch my sister in cross-country competitions which are held early in the morning. One day I'm sure I will wake up early and watch her run."
In Form One, Rebecki showed a keen interest in swimming. But the school's inter-house "round the public estate run" proved to be the turning point. "I was the first runner to complete the course. My teacher was amazed and asked me if I would like to join the cross-country team," says Rebecki. This was followed by two inter-school cross-country victories, and the Jing Ying crown.
Rebecki also tops the junior girls' rankings in the 800 metres and 1,500m, and is a member of the Hong Kong athletics team.
Rebecki will be taking part in the All-Hong Kong Schools Jing Ying Cross-Country Tournament at Tai Lam Country Park (Tai Tong Phase) on Saturday. "Winners of this year's competition can represent Hong Kong in overseas competitions. Top triathletes and athletes from other sports will be present and I need to be much more focused," says Rebecki.
While his sister is going for a second successive Jing Ying title, Stephen wants to lead Ying Wa to victory in his last Jing Ying basketball competition before he leaves secondary school. "In last year's Jing Ying, we lost to our old rivals Diocesan Boys' School. This is my last chance to win this title so I will be ready," he says.
Stephen and Rebecki spend a lot of time together during weekends, but surprisingly sport is not involved. "We watch TV and chat together. Time is too precious for both of us. We think we should relax together," says Stephen.
Their mother, Cindy Chan, says: "I didn't force Rebecki and Stephen to do any sports. My husband and I know little about sports.
"I think Yee-ki's results in running are unbelievable. But you cannot compare them because they are doing different sports. I am pleased to see they are making good use of their talent. I always tell them to have a well-planned timetable to allow for rest and study after training."