Argentina's Diego Schwartzman reacts after losing a point to Spain's Rafael Nadal during their fourth round match at the Australian Open tennis championships in Melbourne, Australia Sunday, Jan. 21, 2018. (AP Photo/Dita Alangkara)
Britain's Kyle Edmund hits a forehand return to Italy's Andreas Seppi during their fourth round match at the Australian Open tennis championships in Melbourne, Australia Sunday, Jan. 21, 2018. (AP Photo/Ng Han Guan)
Britain's Kyle Edmund, left, is congratulated by Italy's Andreas Seppi after winning their fourth round match at the Australian Open tennis championships in Melbourne, Australia Sunday, Jan. 21, 2018. (AP Photo/Ng Han Guan)
Spain's Rafael Nadal celebrates after defeating Argentina's Diego Schwartzman during their fourth round match at the Australian Open tennis championships in Melbourne, Australia Sunday, Jan. 21, 2018. (AP Photo/Dita Alangkara)
Spain's Rafael Nadal makes backhand return to Argentina's Diego Schwartzman during their fourth round match at the Australian Open tennis championships in Melbourne, Australia Sunday, Jan. 21, 2018. (AP Photo/Dita Alangkara)
Croatia's Marin Cilic celebrates after defeating Spain's Pablo Carreno Busta in their fourth round match at the Australian Open tennis championships in Melbourne, Australia Sunday, Jan. 21, 2018. (AP Photo/Ng Han Guan)
Denmark's Caroline Wozniacki hits a forehand return to Slovakia's Magdalena Rybarikova during their fourth round match at the Australian Open tennis championships in Melbourne, Australia Sunday, Jan. 21, 2018. (AP Photo/Dita Alangkara)
Denmark's Caroline Wozniacki blows kisses to the crowd after defeating Slovakia's Magdalena Rybarikova in their fourth round match at the Australian Open tennis championships in Melbourne, Australia Sunday, Jan. 21, 2018. (AP Photo/Dita Alangkara)
Spain's Rafael Nadal celebrates after defeating Argentina's Diego Schwartzman in their fourth round match at the Australian Open tennis championships in Melbourne, Australia Sunday, Jan. 21, 2018. (AP Photo/Dita Alangkara)
Belgium's Elise Mertens makes a forehand return to Croatia's Petra Martic during their fourth round match at the Australian Open tennis championships in Melbourne, Australia Sunday, Jan. 21, 2018. (AP Photo/Andy Brownbill)
Australia's Nick Kyrgios yells in frustration during his fourth round match against Bulgaria's Grigor Dimitrov at the Australian Open tennis championships in Melbourne, Australia Sunday, Jan. 21, 2018.(AP Photo/Andy Brownbill)
Spain's Carla Suarez Navarro, right, shakes hands with Anett Kontaveit of Estonia after she won their fourth round match at the Australian Open tennis championships in Melbourne, Australia Sunday, Jan. 21, 2018. (AP Photo/Dita Alangkara)
Bulgaria's Grigor Dimitrov celebrates after defeating Australia's Nick Kyrgios during his fourth round match at the Australian Open tennis championships in Melbourne, Australia Sunday, Jan. 21, 2018. (AP Photo/Dita Alangkara)
Spain's Carla Suarez Navarro celebrates after defeating Anett Kontaveit of Estonia in their fourth round match at the Australian Open tennis championships in Melbourne, Australia Sunday, Jan. 21, 2018. (AP Photo/Dita Alangkara)
