Photos | Hayden Hopewell and Belinda Ji down reigning Australian junior champions at inaugural 2019 Junior 6s Invitational

It was a case of lightning striking twice at the finals of the inaugural Junior 6s Invitational with Hayden Hopewell and Belinda Ji eliminating the reigning boys and girls Australian junior champions to take their respective titles.

Hopewell and Ji were crowned champions on a dramatic Tuesday afternoon at Cronulla Golf Club that saw a bolt of lightning temporarily halt play midway through the finals.

Australia's newest elite junior golf tournament teed off on Monday with a strong field taking part featuring 72 of Australia's best young male and female players.

The unique format saw competitors play 36 holes of strokeplay on Monday and Tuesday before the top eight girls and boys advanced to 6s matchplay on Tuesday afternoon, a hybrid of the Victorian Open and World Super 6 Perth formats.

In the girls event, Concord golfer Ji was the second seed heading into the matchplay rounds after shooting four under, two shots behind reigning Australian junior champion Hyejun Park.

Ji eliminated Shakira-Ann Kuys and Lion Hugo in her quarter-final and semi-final to advance to the decider against Park.

Park looked in control of the contest at one up with three holes to play but a lost ball on the par five 16th hole halted the 15-year-old's momentum.

An errant tee shot at 17 led to a second conceded hole for Park and put Ji in command heading to the par three 18th only needing a half to secure the title.

Ji fired her tee shot to within four metres of the pin, with Park responding with a close effort of her own. But a missed birdie attempt from Park allowed Ji two putts to win the tournament.

Ji told Golf NSW she was delighted with the victory.

"It's an amazing win for me," she said.

"I had been playing pretty well all day so I knew I might get my chance and I was just going to have to stay patient.

"I haven't really played anything like this before so it feels special to win."

Ji is now looking forward to again teeing it up against professionals, with the win securing her a place in the 2020 Women's NSW Open at Dubbo Golf Club.

In the boys event, Bexley's Harrison Crowe missed out on a place in the finals but St George product Jeffrey Guan made himself the player to beat as the No.1 seed after winning the stroke event, finishing at five under.

But it was to be disaster for the Endeavour Sports High School student, upset in the first match play round by Jacob Dundas in a sudden-death, nearest the pin challenge after their match was halved.

That opened the door for Western Australia's Hopewell, with the 17-year-old beating Lachlan Jones in his quarter-final before accounting for Dundas in his semi-final.

That set up a decider against No. 2 seed Elvis Smylie. Hopewell started strongly and took command of the match before a birdie on 16 put him dormie.

Smylie conceded the final hole to secure a memorable win for Hopewell, overcoming the reigning Australian junior champion in the decider.

Hopewell told Golf NSW it was one of the biggest wins of his young career.

"My game plan for the super 6s was to go for everything, don't hold back and have no regrets," he said.

"It paid off. I ended up being nine under for the 15 holes.

"This win is definitely up there. I won the Jack Newton [International] last year. I'm proud to be the inaugural winner."

The victory earned Hopewell a place in the field for the NSW Open next month and the Gipplsland Super 6s Tour event.

Guan and Park were presented with the Norm Porter Memorial Trophy as winners of the 36-hole stroke event.