Brian, 18, a Form Six student at the Diocesan Boys' School, impressed on his debut, too - winning his first-round junior singles match 6-1, 6-0 against Maxime Hamou, of France, before bowing out to fifth-seeded Hyeon Chung 1-6, 4-6, of South Korea, in the second round.
"It felt really good not to be eliminated at the qualifying stage," says the right-hander. "Playing in the main draw at a grand slam was brilliant; it was a brand new experience for me."
Yet Brian, winner of the boys' singles silver medal at the 2011 National Intercity Games, knew this year would be "now or never" to achieve his dream; next year he'll be too old for junior events.
He played in five ITF tournaments in the past six months to gain enough ranking points so that he could qualify. On January 1, Brian was ranked the 82nd best junior in the world - good enough for a place in the Australian Open's junior singles' qualifying tournament.
Eight qualifying spots are left open in the main draw of 64 players. The world's top 48 players enter automatically, with a further six players given wildcards. Two more places go to the two outstanding performers at the AGL Loy Yang Traralgon International, held in Melbourne the week before.
"I hesitated about going to play in the qualifiers," Brian says. "My regular doubles partner, Kevin Wong Chun-hun, faced the same choice and opted not to."
"However, I knew that it was my only chance to try to play in the juniors' event at the Australian Open; next year I'll be over age. So I decided I must try."
Brian received a first round bye in qualifying - thanks to him being seeded fourth. Then he won two qualifying matches - "both three-set thrillers" - to reach the first round of the main draw.
"That bye meant I wasn't as tired as my opponent, Chayanon Kaewsuto, of Thailand, in our second-round match, and I beat him 6-2, 4-6, 6-4," says Brian. In his last qualifier, he defeated Australia's Thomas Fancutt 4-6, 6-2, 6-2.
"I was very worried I'd be knocked out in my very first match; I wanted to play at the famous Melbourne Park so badly and I didn't want to pack my stuff and head back to Hong Kong after playing only one match," Brian says.
Playing in the main draw not only earned him a player's pass, but the chance to see some top players close-up, including Jo-Wilfried Tsonga, of France, and champion Novak Djokovic, of Croatia, as he practiced before his early matches.
Qualifying in the singles also earned him a place in the junior doubles. He teamed up with Filipino Jurence Zosimo Mendoza, and lost the quarter final.
"I am satisfied overall," Brian says. "My goal was to qualify for the main draw - and I managed to do that."
Brian hopes to play at this year's three other junior grand-slam tournaments, including Wimbledon, in Britain.
However, academic pressures may hit his chances. He has an unconditional offer from Harvard University, in the United States - as long as he maintains his academic targets.
"I must keep studying hard for my HKDSE in April, so it may mean I drop down the tennis rankings," he says. "And that, unfortunately, might affect my chances of playing at Wimbledon."