Belgium's Elise Mertens, left, is congratulated by Ukraine's Elina Svitolina after winning their quarterfinal at the Australian Open tennis championships in Melbourne, Australia, Tuesday, Jan. 23, 2018. (AP Photo/Dita Alangkara)
Belgium's Elise Mertens reacts after winning a point against Ukraine's Elina Svitolina during their quarterfinal at the Australian Open tennis championships in Melbourne, Australia, Tuesday, Jan. 23, 2018. (AP Photo/Dita Alangkara)
Belgium's Elise Mertens hits forehand return to Ukraine's Elina Svitolina during their quarterfinal at the Australian Open tennis championships in Melbourne, Australia, Tuesday, Jan. 23, 2018. (AP Photo/Dita Alangkara)
El español Rafael Nadal celebra su victoria sobre el argentino Diego Schwartzman en la cuarta ronda del Abierto de Australia el domingo 21 de enero de 2018 en Melbourne. (AP Foto/Dita Alangkara)
Ukraine's Elina Svitolina reacts after losing a point to Belgium's Elise Mertens during their quarterfinal at the Australian Open tennis championships in Melbourne, Australia, Tuesday, Jan. 23, 2018. (AP Photo/Andy Brownbill)
Ukraine's Elina Svitolina reaches for a return to Belgium's Elise Mertens during their quarterfinal at the Australian Open tennis championships in Melbourne, Australia, Tuesday, Jan. 23, 2018. (AP Photo/Vincent Thian)
Belgium's Elise Mertens celebrates after defeating Ukraine's Elina Svitolina in their quarterfinal at the Australian Open tennis championships in Melbourne, Australia, Tuesday, Jan. 23, 2018. (AP Photo/Dita Alangkara)
Ukraine's Elina Svitolina waves as she leaves Rod Laver Arena following her quarterfinal loss to Belgium's Elise Mertens at the Australian Open tennis championships in Melbourne, Australia, Tuesday, Jan. 23, 2018. (AP Photo/Dita Alangkara)
Belgium's Elise Mertens celebrates after winning a point against Ukraine's Elina Svitolina during their quarterfinal at the Australian Open tennis championships in Melbourne, Australia, Tuesday, Jan. 23, 2018. (AP Photo/Dita Alangkara)
Belgium's Elise Mertens celebrates after defeating Ukraine's Elina Svitolina in their quarterfinal at the Australian Open tennis championships in Melbourne, Australia, Tuesday, Jan. 23, 2018. (AP Photo/Dita Alangkara)
