United States' Madison Keys serves to France's Caroline Garcia during their fourth round match at the Australian Open tennis championships in Melbourne, Australia, Monday, Jan. 22, 2018. (AP Photo/Andy Brownbill)
Tomas Berdych of the Czech Republic reacts after defeating Italy's Fabio Fognini during their fourth round match at the Australian Open tennis championships in Melbourne, Australia, Monday, Jan. 22, 2018. (AP Photo/Vincent Thian)
United States' Madison Keys walks on the court between games as she plays France's Caroline Garcia during their fourth round match at the Australian Open tennis championships in Melbourne, Australia, Monday, Jan. 22, 2018. (AP Photo/Dita Alangkara)
Switzerland's Roger Federer celebrates after defeating Hungary's Marton Fucsovics in their fourth round match at the Australian Open tennis championships in Melbourne, Australia, Monday, Jan. 22, 2018.(AP Photo/Dita Alangkara)
France's Caroline Garcia makes a forehand return to United States' Madison Keys during their fourth round match at the Australian Open tennis championships in Melbourne, Australia Monday, Jan. 22, 2018. (AP Photo/Andy Brownbill)
Taiwan's Hsieh Su-wei makes a backhand return to Germany's Angelique Kerber during their fourth round match at the Australian Open tennis championships in Melbourne, Australia, Monday, Jan. 22, 2018. (AP Photo/Dita Alangkara)
Austria's Dominic Thiem reacts in frustration during his fourth round match against United States' Tennys Sandgren at the Australian Open tennis championships in Melbourne, Australia, Monday, Jan. 22, 2018. (AP Photo/Vincent Thian)
Germany's Angelique Kerber reacts after losing a point to Taiwan's Hsieh Su-wei during their fourth round match at the Australian Open tennis championships in Melbourne, Australia, Monday, Jan. 22, 2018. (AP Photo/Dita Alangkara)
France's Caroline Garcia serves to United States' Madison Keys during their fourth round match at the Australian Open tennis championships in Melbourne, Australia Monday, Jan. 22, 2018. (AP Photo/Dita Alangkara)
United States' Tennys Sandgren celebrates after defeating Austria's Dominic Thiem in their fourth round match at the Australian Open tennis championships in Melbourne, Australia, Monday, Jan. 22, 2018. (AP Photo/Vincent Thian)
