Japan's Kei Nishikori reacts after his men's singles tennis match against USA's Frances Tiafoe at the ATP Tour Japan Open Tennis Championships at the Ariake Tennis Forest Park in Tokyo on October 1, 2026. Nishikori announced his retirement from the sport after the tournament. (Photo by Rie KIKUCHI / AFP via Getty Images)

Japan's Kei Nishikori gestures as he retires from the sport after his men's singles tennis match against USA's Frances Tiafoe at the ATP Tour Japan Open Tennis Championships at the Ariake Tennis Forest Park in Tokyo on October 1, 2026. (Photo by Rie KIKUCHI / AFP via Getty Images)

Japan's Kei Nishikori waves to fans as he retires from the sport after his men's singles tennis match against USA's Frances Tiafoe at the ATP Tour Japan Open Tennis Championships at the Ariake Tennis Forest Park in Tokyo on October 1, 2026. (Photo by Rie KIKUCHI / AFP via Getty Images)

BEIJING, CHINA - OCTOBER 01: Mariano Navone of Argentina plays a forehand against Alex De Minaur of Australia during the Men's Singles first round match on Day 2 of the China Open at National Tennis Center on October 01, 2026 in Beijing, China. (Photo by Yanshan Zhang/Getty Images)

BEIJING, CHINA - OCTOBER 01: Alex De Minaur of Australia plays a forehand against Mariano Navone of Argentina during the Men's Singles first round match on Day 2 of the China Open at National Tennis Center on October 01, 2026 in Beijing, China. (Photo by Yanshan Zhang/Getty Images)

BEIJING, CHINA - OCTOBER 01: Mariano Navone of Argentina plays a forehand against Alex De Minaur of Australia during the Men's Singles first round match on Day 2 of the China Open at National Tennis Center on October 01, 2026 in Beijing, China. (Photo by Yanshan Zhang/Getty Images)

BEIJING, CHINA - OCTOBER 01: Mariano Navone of Argentina plays a forehand against Alex De Minaur of Australia during the Men's Singles first round match on Day 2 of the China Open at National Tennis Center on October 01, 2026 in Beijing, China. (Photo by Yanshan Zhang/Getty Images)

BEIJING, CHINA - OCTOBER 01: Mariano Navone of Argentina plays a forehand against Alex De Minaur of Australia during the Men's Singles first round match on Day 2 of the China Open at National Tennis Center on October 01, 2026 in Beijing, China. (Photo by Yanshan Zhang/Getty Images)