Naomi Osaka knocked out by Amanda Anisimova

At the Australian Open, defending champion Naomi Osaka was unable to advance to a much-anticipated fourth-round match against top-ranked Ash Barty.

When Amanda Anisimova a 20-year-old American rated 60th in the world, upset the four-time major winner 4-6, 6-3, 7-6 on Friday, she guaranteed that the so-called final-before-the-final didn't happen

After dropping the first set, Anisimova realised she needed to step up her game or risk being knocked out of the event.

In the third set, Anisimova averted two match chances by serving to remain in the match and finishing with an ace. She has 46 victories compared to 21 for Osaka.

She had a long break after losing in the third round of the US Open and entered the year's first major with a seeding of No. 13.

In the first three rounds at Melbourne Park, Barty has only lost eight games and spent less than three hours on the court.

The 2019 French Open champion and Wimbledon champion is trying to become the first Australian woman to win her home tournament since 1978.

Victoria Azarenka, the two-time Australian Open winner, defeated 15th-seeded Elina Svitolina 6-0, 6-2 to reach the fourth round at Melbourne Park for the first time since 2016.

In the press conference room, five-year-old Leo, wearing sunglasses and sitting on his mother's knee, answered succinctly: "Awesome!"