Czech Republic's Tomas Berdych, right, looks at Switzerland's tennis player Roger Federer, center, hitting a ball to his fans at the Old Town Square in Prague, Czech Republic, Monday, Feb. 20, 2017. Federer arrived in Prague to promote the Laver Cup, a tournament that will be held in Prague on Sept. 22 to 24, 2017, pitting six top European players against their counterparts from the rest of the world. (AP Photo/Petr David Josek)