Amanda Anisimova stunned defending champion Naomi Osaka in three sets Friday to reach the fourth round of the 2022 Australian Open at Melbourne Park.
Anisimova, whose best result in a Grand Slam is a semifinal appearance at the 2019 French Open, dropped the opening set against Osaka before storming back to win the next two, including the third set in a tiebreaker. The 20-year-old American finished with 46 winners and 11 aces in the upset.
Osaka, a four-time major champion, was eliminated in the third round or earlier for her third straight Grand Slam appearance since winning last year's Australian Open.
It marked the second straight upset and impressive performance by Anisimova, who knocked out No. 22 Belinda Bencic in straight sets in her previous match. Osaka was seeded 13th but has reached as high as No. 1 in the WTA Tour rankings.
"I knew I had to be playing sharp if I wanted to give myself a chance," Anisimova told reporters after the 4-6, 6-3, 7-6 (5) triumph.
The New Jersey native matched her best career showing in the Australian Open with an aggressive play style. She pushed the envelope on Osaka's serve, which allowed her to win 31 percent of points on the return, including eight return winners.
Anisimova will next face top-seeded Australian Ashleigh Barty for a spot in the quarterfinals.
Osaka was playing just her second competitive event since last year's U.S. Open following a hiatus to focus on her mental health. She withdrew from the Melbourne Summer Set warm-up event earlier in January after reaching the semifinals because of an abdominal injury.
The 24-year-old Japanese superstar had her chances, including a pair of match points in the third set, but she couldn't come up with the clutch point she needed to close out her unseeded opponent. She also converted just one of the 10 break points she generated.
Osaka still emerged happy with her overall performance.
"Definitely I think I fought for every point and I can't be sad about that," she said. "I'm not God. I can't win every match. So I just have to, like, take that into account and know that it would be nice to win the tournament, but that's, like, really special."
The two-time Australian Open champion also confirmed she's planning to play the full 2022 schedule.
"I just want to go into this year knowing that I'll play the whole year and I'll just have the greatest attitude ever," Osaka said. "I'll fight for every point, and even if I win or lose, I'll just go off court trying the best I could. And there's no way anyone can expect anything more of me because they saw how hard I fought."
Her next Grand Slam challenge will be the French Open in May. She's yet to advance beyond the third round in the clay-court major through five career appearances.