Ukraine's Marta Kostyuk has duplicated the feat of Croatian Mirjana Lucic-Baroni 20 years ago, when she won the Australian Open girls' singles title at age 14, while Hungary's Zsombor Piros has won his country's first Australian Open boys' championship.
Kostyuk, 14, used powerful groundstrokes to outlast top-seeded Rebeka Masarova of Switzerland 7-5, 1-6, 6-4 at Rod Laver Arena on Saturday.
Lucic-Baroni, a surprise women's singles semifinalist this year, was also 14 when she beat Germany's Marlene Weingartner 6-2, 6-2 in the 1997 Australian junior final.
Kostyuk, who broke Masarova's serve in the ninth game of the final set, is the first Ukrainian player to win the Australian Open girls' title.
In the boys' championship, Piros, the 15th seed, had to work for almost two hours to beat fourth-seeded Yshai Oliel of Israel 4-6, 6-4, 6-3.
It was only the second Grand Slam junior event for the 17-year-old from Budapest. He lost in the second round at Melbourne Park last year.
The opening set was the only one Piros lost on his way to the title. He beat the second and fifth seeds before outslugging the Israeli left-hander in the final.
Oliel, who beat top-seeded Wu Yibing of China in the semifinals, proved less steady than his opponent in the long baseline rallies.
With the title in the balance at 1-1 in the deciding set, Piros slumped to 0-40. The right-hander, who lists magic tricks among his hobbies, found a way to scramble out of that service game and grew in confidence from there.
He broke for 4-2 and was untroubled in the next two service games to close out the match.
The Associated Press contributed to this report.