Naomi Osaka of Japan reacts after missing a point during her match against Maria Sakkari of Greece at the Brisbane International tennis tournament in Brisbane, Australia, Tuesday, Jan. 7, 2020. (AP Photo/Tertius Pickard)
The Associated Press
BRISBANE, Australia (AP) - Naomi Osaka got an extended workout in her opening match at the Brisbane International, just two weeks away from the defense of her Australia Open title.
Osaka defeated Greece's Maria Sakkari 6-2, 6-7 (4), 6-3 on Tuesday to set up a second-round match with American Sofia Kenin.
The two-time Grand Slam champion and former world No. 1 took more than two hours and had 16 aces to beat Sakkari.
In other matches Tuesday, eighth-seeded Madison Keys beat Czech qualifier Maria Bouzkova 6-2, 6-3. Keys will now face local favorite Samantha Stosur in the second round.
"Sam's always tough," Keys said. "I think she's beaten me every time we have played. It's also hard to play someone who is going to be playing at home and have the crowd and all that."
Russian qualifier Liudmila Samsonova had the upset of the tournament so far by defeating American Sloane Stephens, the 2017 U.S. Open champion, 6-4, 2-6, 6-3.
In later matches, two-time Wimbledon champion Petra Kvitova beat Anastasia Pavlyuchenkova 2-6, 6-1, 6-0 and American qualifier Jennifer Brady beat wild-card entry Maria Sharapova 3-6, 6-1, 7-6 (4).
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Naomi Osaka of Japan reacts after missing a shot during her match against Maria Sakkari of Greece at the Brisbane International tennis tournament in Brisbane, Australia, Tuesday, Jan. 7, 2020. (AP Photo/Tertius Pickard)
The Associated Press
Naomi Osaka of Japan plays a shot during her match against Maria Sakkari of Greece at the Brisbane International tennis tournament in Brisbane, Australia, Tuesday, Jan. 7, 2020. (AP Photo/Tertius Pickard)
The Associated Press
Naomi Osaka of Japan plays a shot during her match against Maria Sakkari of Greece at the Brisbane International tennis tournament in Brisbane, Australia, Tuesday, Jan. 7, 2020. (AP Photo/Tertius Pickard)
The Associated Press
Maria Sharapova of Russia reacts after winning a point during her match against Jennifer Brady of the United States at the Brisbane International tennis tournament in Brisbane, Australia, Tuesday, Jan. 7, 2020. (AP Photo/Tertius Pickard)
The Associated Press
Maria Sharapova of Russia plays a shot during her match against Jennifer Brady of the United States at the Brisbane International tennis tournament in Brisbane, Australia, Tuesday, Jan. 7, 2020. (AP Photo/Tertius Pickard)
The Associated Press
Naomi Osaka of Japan plays a shot during her match against Maria Sakkari of Greece at the Brisbane International tennis tournament in Brisbane, Australia, Tuesday, Jan. 7, 2020. (AP Photo/Tertius Pickard)
The Associated Press
Jennifer Brady of the United States plays a shot during her match against Maria Sharapova of Russia at the Brisbane International tennis tournament in Brisbane, Australia, Tuesday, Jan. 7, 2020. (AP Photo/Tertius Pickard)
The Associated Press
Maria Sharapova of Russia plays a shot during her match against Jennifer Brady of the United States at the Brisbane International tennis tournament in Brisbane, Australia, Tuesday, Jan. 7, 2020. (AP Photo/Tertius Pickard)
The Associated Press
Maria Sharapova of Russia serves during her match against Jennifer Brady of the United States at the Brisbane International tennis tournament in Brisbane, Australia, Tuesday, Jan. 7, 2020. (AP Photo/Tertius Pickard)
The Associated Press