Nicolson is just two wins away from reaching the gold-medal bout, while the first, third and fourth seeds have notably already been eliminated from the tournament.

The 2018 Commonwealth Games champion next faces Brit Karriss Artingstall in Wednesday night's quarter-final.

Nicolson was all smiles after her split-decision triumph on Monday night, having lifted when it mattered most to ensure every judge deemed her the winner of the deciding final round.

Four of five judges gave Nicolson the overall win.

The 25-year-old celebrated at the Kokugikan Arena then turned to the camera, wishing her father happy birthday before blowing a kiss.

The Queenslander is following in the footsteps of her late older brother Jamie, who boxed for Australia at the 1992 Olympics.

Skye's brothers Jamie and Gavin tragically died in a car accident while en route to boxing training in 1994, a year before she was born.

"It's unreal. It's a pretty crazy story and I'm just so glad that I can be here, making my family proud and making Jamie proud," Nicolson said.

"My whole boxing career has been building up to this moment.

"I know everyone is watching at home and I can't wait to go talk to them."

The 25-year-old, who described her connection with Jamie as being special, noted a "day full of upsets" proved 'this division is very open'.

"My next opponent is a very strong competitor who has won world-stage medals, so I am in for a very tough fight," Nicolson said.

"But I'm ready to give it everything."

Nicolson landed a jab to the face late in the second round then connected with a few lefts in the final round to trump the South Korean, who was warned over a punch to the back of the head early in the fight.

Earlier on Monday, Australian flyweight Alex Winwood's first Olympics ended with a split-decision loss to Zambia's Patrick Chinyemba.

Dissenting Thai judge Karn Naklam deemed Winwood the winner after three tight rounds.

But the remaining four judges gave the victory to Chinyemba, whose fancy footwork and reach helped secure a spot in the round of 16.

Chinyemba was adjudicated a 29-28 winner on three scorecards, while that was the same margin that Naklam settled on.

Winwood rallied after being outgunned in the opening round, winning the second round in the eyes of all but one judge.

But the 24-year-old West Australian failed to land enough blows to achieve the same result in the deciding round.

Australian Associated Press