Australia's Ashleigh Barty celebrates after her match against Alison Riske of the U.S. during Australian Open in Fourth Round at Melbourne Park, Melbourne, Australia, January 26, 2020. World number one Ash Barty celebrated Australia Day with a comeback win on Sunday, defeating Alison Riske 6-3 1-6 6-4 to make the Australian Open quarter-final for the second year in a row. REUTERS/Kai Pfaffenbach

Australia's Ashleigh Barty in action during her match against Alison Riske of the U.S. during Australian Open in Fourth Round at Melbourne Park, Melbourne, Australia, January 26, 2020. World number one Ash Barty celebrated Australia Day with a comeback win on Sunday, defeating Alison Riske 6-3 1-6 6-4 to make the Australian Open quarter-final for the second year in a row. REUTERS/Issei Kato

Australia's Ashleigh Barty in action during her match against Alison Riske of the U.S. during Australian Open in Fourth Round at Melbourne Park, Melbourne, Australia, January 26, 2020. World number one Ash Barty celebrated Australia Day with a comeback win on Sunday, defeating Alison Riske 6-3 1-6 6-4 to make the Australian Open quarter-final for the second year in a row. REUTERS/Kai Pfaffenbach

Australia's Ashleigh Barty in action during her match against Alison Riske of the U.S. during Australian Open in Fourth Round at Melbourne Park, Melbourne, Australia, January 26, 2020. World number one Ash Barty celebrated Australia Day with a comeback win on Sunday, defeating Alison Riske 6-3 1-6 6-4 to make the Australian Open quarter-final for the second year in a row. REUTERS/Issei Kato

Australia's Ashleigh Barty celebrates after her match against Alison Riske of the U.S. during Australian Open in Fourth Round at Melbourne Park, Melbourne, Australia, January 26, 2020. World number one Ash Barty celebrated Australia Day with a comeback win on Sunday, defeating Alison Riske 6-3 1-6 6-4 to make the Australian Open quarter-final for the second year in a row. REUTERS/Issei Kato

Australia's Ashleigh Barty shakes hands with Alison Riske of the U.S. after their Australian Open match in Fourth Round at Melbourne Park, Melbourne, Australia, January 26, 2020. World number one Ash Barty celebrated Australia Day with a comeback win on Sunday, defeating Alison Riske 6-3 1-6 6-4 to make the Australian Open quarter-final for the second year in a row. REUTERS/Kai Pfaffenbach