Ben Shelton serves during the men's singles semifinal match between Alexander Zverev of Germany and Ben Shelton of the United States at Boss Open 2025 tennis tournament in Stuttgart, Germany, June 14, 2025. (Photo by Philippe Ruiz/Xinhua)

Ben Shelton reacts during the men's singles semifinal match between Alexander Zverev of Germany and Ben Shelton of the United States at Boss Open 2025 tennis tournament in Stuttgart, Germany, June 14, 2025. (Photo by Philippe Ruiz/Xinhua)

Ben Shelton hits a return during the men's singles semifinal match between Alexander Zverev of Germany and Ben Shelton of the United States at Boss Open 2025 tennis tournament in Stuttgart, Germany, June 14, 2025. (Photo by Philippe Ruiz/Xinhua)

Alexander Zverev celebrates after winning the men's singles semifinal match between Alexander Zverev of Germany and Ben Shelton of the United States at Boss Open 2025 tennis tournament in Stuttgart, Germany, June 14, 2025. (Photo by Philippe Ruiz/Xinhua)

Alexander Zverev celebrates after winning the men's singles semifinal match between Alexander Zverev of Germany and Ben Shelton of the United States at Boss Open 2025 tennis tournament in Stuttgart, Germany, June 14, 2025. (Photo by Philippe Ruiz/Xinhua)

Alexander Zverev hits a return during the men's singles semifinal match between Alexander Zverev of Germany and Ben Shelton of the United States at Boss Open 2025 tennis tournament in Stuttgart, Germany, June 14, 2025. (Photo by Philippe Ruiz/Xinhua)

Alexander Zverev reacts during the men's singles semifinal match between Alexander Zverev of Germany and Ben Shelton of the United States at Boss Open 2025 tennis tournament in Stuttgart, Germany, June 14, 2025. (Photo by Philippe Ruiz/Xinhua)

Alexander Zverev hits a return during the men's singles semifinal match between Alexander Zverev of Germany and Ben Shelton of the United States at Boss Open 2025 tennis tournament in Stuttgart, Germany, June 14, 2025. (Photo by Philippe Ruiz/Xinhua)

Alexander Zverev hits a return during the men's singles semifinal match between Alexander Zverev of Germany and Ben Shelton of the United States at Boss Open 2025 tennis tournament in Stuttgart, Germany, June 14, 2025. (Photo by Philippe Ruiz/Xinhua)

Alexander Zverev hits a return during the men's singles semifinal match between Alexander Zverev of Germany and Ben Shelton of the United States at Boss Open 2025 tennis tournament in Stuttgart, Germany, June 14, 2025. (Photo by Philippe Ruiz/Xinhua)

Alexander Zverev serves during the men's singles semifinal match between Alexander Zverev of Germany and Ben Shelton of the United States at Boss Open 2025 tennis tournament in Stuttgart, Germany, June 14, 2025. (Photo by Philippe Ruiz/Xinhua)

Alexander Zverev hits a return during the men's singles semifinal match between Alexander Zverev of Germany and Ben Shelton of the United States at Boss Open 2025 tennis tournament in Stuttgart, Germany, June 14, 2025. (Photo by Philippe Ruiz/Xinhua)

Taylor Fritz returns a shot during the men's singles semi-final match between Felix Auger-Aliassime of Canada and Taylor Fritz of the United States at Boss Open 2025 tennis tournament in Stuttgart, Germany, June 14, 2025. (Photo by Philippe Ruiz/Xinhua)

Taylor Fritz returns a shot during the men's singles semi-final match between Felix Auger-Aliassime of Canada and Taylor Fritz of the United States at Boss Open 2025 tennis tournament in Stuttgart, Germany, June 14, 2025. (Photo by Philippe Ruiz/Xinhua)

Taylor Fritz celebrates after the men's singles semi-final match between Felix Auger-Aliassime of Canada and Taylor Fritz of the United States at Boss Open 2025 tennis tournament in Stuttgart, Germany, June 14, 2025. (Photo by Philippe Ruiz/Xinhua)

Felix Auger-Aliassime reacts during the men's singles semi-final match between Felix Auger-Aliassime of Canada and Taylor Fritz of the United States at Boss Open 2025 tennis tournament in Stuttgart, Germany, June 14, 2025. (Photo by Philippe Ruiz/Xinhua)

Taylor Fritz returns a shot during the men's singles semi-final match between Felix Auger-Aliassime of Canada and Taylor Fritz of the United States at Boss Open 2025 tennis tournament in Stuttgart, Germany, June 14, 2025. (Photo by Philippe Ruiz/Xinhua)

Felix Auger-Aliassime returns a shot during the men's singles semi-final match between Felix Auger-Aliassime of Canada and Taylor Fritz of the United States at Boss Open 2025 tennis tournament in Stuttgart, Germany, June 14, 2025. (Photo by Philippe Ruiz/Xinhua)

Felix Auger-Aliassime returns a shot during the men's singles semi-final match between Felix Auger-Aliassime of Canada and Taylor Fritz of the United States at Boss Open 2025 tennis tournament in Stuttgart, Germany, June 14, 2025. (Photo by Philippe Ruiz/Xinhua)

Felix Auger-Aliassime returns a shot during the men's singles semi-final match between Felix Auger-Aliassime of Canada and Taylor Fritz of the United States at Boss Open 2025 tennis tournament in Stuttgart, Germany, June 14, 2025. (Photo by Philippe Ruiz/Xinhua)

Felix Auger-Aliassime serves during the men's singles semi-final match between Felix Auger-Aliassime of Canada and Taylor Fritz of the United States at Boss Open 2025 tennis tournament in Stuttgart, Germany, June 14, 2025. (Photo by Philippe Ruiz/Xinhua)

Taylor Fritz returns a shot during the men's singles semi-final match between Felix Auger-Aliassime of Canada and Taylor Fritz of the United States at Boss Open 2025 tennis tournament in Stuttgart, Germany, June 14, 2025. (Photo by Philippe Ruiz/Xinhua)

Taylor Fritz returns a shot during the men's singles semi-final match between Felix Auger-Aliassime of Canada and Taylor Fritz of the United States at Boss Open 2025 tennis tournament in Stuttgart, Germany, June 14, 2025. (Photo by Philippe Ruiz/Xinhua)