Back in 2009, Mark was a Form One student at Diocesan Boys' School, and he was already impressing on the pitch. His outstanding performances earned him a chance to represent his school in the All Hong Kong Schools Jing Ying Football Tournament, the top inter-school competition, in his first year at DBS.
For many players, doing well locally is all they want to achieve, but Mark set his sights on playing overseas. Mark's father is a firefighter and his mother is a housewife, so they could not afford Mark's studies and training overseas.
It was only when Mark won a Dreams Come True scholarship three years ago that he had the chance to make his dreams come true.
The scholarship allowed Mark to complete his high school studies in Britain at the Brooke House College Football Academy. Thanks to the scholarship, Mark does not pay any tuition fees or accommodation costs.
Growing up in Tuen Mun, Mark started playing football at the age of six. His elder brother Tan Ka-lok started training later, when he was in Form One, and he got to play for First Division clubs Eastern and Sun Hei. However, Ka-lok now plays for Second Division club Wing Yee.
Compared to Ka-lok, Mark seems to have had a smoother career path. Mark was signed by English Football League Championship club Peterborough United and joined its junior team for a year in the 2009/2010 season.
During his summer vacation this year, he was called up for training with the Hong Kong under-21 squad and played a friendly match against the Australian under-19 squad. With these signings and international call-ups, Mark looks like he is on track for a successful career in football.
Competition between players is extremely intense in Britain, says Mark. "As a foreign player in the UK, I know that I have to play better than most local players in a club just to stay," Mark says. "If both me and a local player are at the same level, managers and coaches will prefer to choose a local boy."
At 1.75 metres tall, Mark is not sure how far away he is from fulfilling his dream of a professional career in English football, but he says he is much closer to it than if he was only training in Hong Kong. "In Hong Kong, players have to train for school teams, clubs and then the Hong Kong youth team," he says. "Sometimes they have to travel a lot after school to training sessions. A lot of time is spent on transport and that was my daily routine, too, before I went to Brooke House.
"But in the UK, players in the football academy live and study together, just like those who are playing for top clubs. No-one is late for matches for any reason as we travel to the games together by coach. Besides, for every match we have a very detailed briefing - the coach gives everyone who is starting a game a separate note, telling you what he is looking for and your role in the team. We also have lessons in tactics, so we have more of an ability to analyse matches."
According to Mark, many British clubs make their young players write a self-evaluation after each match to reflect on their performance and tell the coaches what they achieved in a match, and how they did it.
Britain's emphasis on sport science has also helped Mark's development.
"I learned that the performance of players could be affected by food and rest to a large extent," Mark says.
"I always drink water and replenish my energy. Protecting my body and staying fit are always my top concerns."
Now in the upper sixth-form, the final year of school in Britain, Mark has just a few months left at Brooke House. Besides preparing for his A-level exams next summer, he is making an effort to demonstrate his skills to English clubs in order to secure a full-time contract.
"This is now a crucial moment and probably another turning point in my career," Mark says. "I hope I will have good news by the end of December."