Czech Republic's Tomas Machac (R) retires from his men's singles semi-final match against USA's Taylor Fritz as they embrace before walking off court at the United Cup tennis tournament on Ken Rosewall Arena in Sydney on January 4, 2025. (Photo by Steve CHRISTO / AFP) / -- IMAGE RESTRICTED TO EDITORIAL USE - STRICTLY NO COMMERCIAL USE -- (Photo by STEVE CHRISTO/AFP via Getty Images)