American Amanda Anisimova is advancing to face top-ranked Ash Barty after defeating defending champion Naomi Osaka in the third round at the Australian Open on Friday.

According to the Associated Press, the four-time Grand Slam champion was knocked out of the tournament by the 20-year-old who won 4-6, 6-3, 7-6 (5).

Ranked 60th globally, Anisimova lost the first set before storming back to win the following two sets and clinching the win in the third set in a tiebreaker.

The 20-year-old finished with 46 winners to Osaka's 21.

Anisimova will now face Barty, who defeated Italy's Camila Giorgi 6-2, 6-3.

The news outlet reported that the Australian Open was the first major tournament Osaka played in this year, returning to the game in January after taking a four-month break.

After losing in the third round at the U.S Open in September, the 24-year-old withdrew in the second round of the French Open and skipped Wimbledon to focus on her mental health.