MELBOURNE, Australia (AP) -- Delray Beach-native Coco Gauff has beaten defending champion Naomi Osaka 6-3, 6-4 to reach the fourth round of the Australian Open.
It was the second upset with hours on Rod Laver Arena.
Two matches earlier, 23-time major winner Serena Williams was beaten in three sets by Wang Qiang.
The 15-year-old Gauff lost to Osaka at the U.S. Open last year. This time, she was too good.
Osaka has now failed to defend her two major titles at the U.S. Open and in Australia.
Gauff already beat another former No. 1 in the first round this week when she got past Venus Williams.
This is only the third Grand Slam tournament of Gauff's career but already her second time reaching the fourth round.
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The moment when rising star @CocoGauff clinched match point against 2019 champion Naomi Osaka.#AO2020 | #AusOpen | @channel9 | @espn pic.twitter.com/zVDOlvNEl8
— #AusOpen (@AustralianOpen) January 24, 2020