Like a war cry, "ultimate!" rings out across the field as a disc is flung into the air, and two teams of seven thunder towards each other. A game of ultimate frisbee has begun.
You might be more familiar with casually tossing a frisbee around at the beach, or playing catch with the dog in a park. However, to others, that disc represents the long throws, high leaps and dramatic dives that characterise the sport of ultimate frisbee, or simply "ultimate".
Since it began in 1968, ultimate has grown into a fast-paced, exhilarating mix of fun and competitiveness, played by millions of amateurs and professionals worldwide.
The rules are reasonably simple: each team needs seven male and female players, mixing at least two of one gender with five of the other. This makes it one of the few mixed-gender professional sports.
A match lasts an hour or until a team scores 11 points. The game begins with "the pull", when one team throws the disc across the length of the field (about the size of a football pitch) to the opposing team. That team then passes the disc between team members - a player holding the disc cannot run or "travel" with it, so their teammates move into open space to receive the pass.
A player may only hold the disc for 10 seconds, so quick thinking and speed around the pitch are essential. If the player holds it for too long, drops it, travels with it, or the pass is intercepted, the other team gets a chance to score. A team wins a point when they successfully catch the frisbee in their opponents' end zone.
The sport originated in the United States, but it is becoming increasingly popular worldwide. Brian Lau, a Year 12 student at Chinese International School, is passionate about promoting ultimate in Hong Kong.
Brian started playing three years ago at summer school in the US. His enthusiasm led him to launch the Chinese International School Frisbee team in 2013 during his year on the mainland at the CIS Hangzhou programme. "We started playing ultimate in Hangzhou just for fun, but Justin Choo - a great friend of mine - and I wanted to take Ultimate to another level."
Three weeks after its inception, the team entered a national tournament in Wuhan, which, they discovered on arrival, was for adults. Against tough opposition, they won only one match, but their achievement was recognised when they were awarded the tournament's spirit trophy.
The Wuhan experience was only the beginning. Early last year, the team finished third in the Shanghai Youth Open, the mainland's largest youth frisbee tournament. Back in Hong Kong, they won the Hong Kong Inter-schools Tournament. This year, the team revisited the Shanghai Youth Open, and defeated a previously unbeaten team in the finals to be crowned champion.
Brian values his team's sportsmanship and passion for the game over their victories (unusually, the sport is self-officiating - there is no referee - so a spirit of fair play is essential).
His favourite moment to date was the celebration at the Shanghai Youth Open where everyone rushed onto the field, crowded into a circle and started cheering and jumping. "I could not have been more proud of how far our team had come. I could tell every member of our team was celebrating with pure joy."
Brian wants other people to feel that joy, so last autumn, he organised a "Frisbee Carnival" to promote the sport among more students.
"I knew that I couldn't suddenly make ultimate popular. Starting with our community would be a fundamental basis for the future development of the sport," says Brian. "Ultimate brings people together really easily. It helps you make new friends, as well as get some exercise."
In Hong Kong, the number of junior ultimate players is steadily rising, with more than 10 school teams currently competing. If it sounds fun to you, Brian only has words of encouragement. "Don't be afraid to go for the first time. Everyone in the ultimate community would be extremely glad to see new people picking up the sport!"
So, see you on the pitch!
The Hong Kong Ultimate Players' Association regularly runs teaching programmes and friendly games.