Germany's Alexander Zverev returns the ball to Italy's Luciano Darderi during the men's singles round of 16 tennis match on day nine of the US Open tennis tournament at the USTA Billie Jean King National Tennis Center in New York City on September 7, 2026. (Photo by CHARLY TRIBALLEAU / AFP via Getty Images)

Germany's Alexander Zverev returns the ball to Italy's Luciano Darderi during the men's singles round of 16 tennis match on day nine of the US Open tennis tournament at the USTA Billie Jean King National Tennis Center in New York City on September 7, 2026. (Photo by CHARLY TRIBALLEAU / AFP via Getty Images)

NEW YORK, NEW YORK - SEPTEMBER 07: Learner Tien of the United States reacts after being defeated by Karen Khachanov during their Men's Singles Fourth Round match on Day Nine of the 2026 US Open at USTA Billie Jean King National Tennis Center on September 07, 2026 in the Flushing neighborhood of the Queens borough of New York City. (Photo by Matthew Stockman/Getty Images)

NEW YORK, NEW YORK - SEPTEMBER 07: Learner Tien of the United States reacts after being defeated by Karen Khachanov during their Men's Singles Fourth Round match on Day Nine of the 2026 US Open at USTA Billie Jean King National Tennis Center on September 07, 2026 in the Flushing neighborhood of the Queens borough of New York City. (Photo by Matthew Stockman/Getty Images)

NEW YORK, NEW YORK - SEPTEMBER 07: Learner Tien of the United States reacts after being defeated by Karen Khachanov during their Men's Singles Fourth Round match on Day Nine of the 2026 US Open at USTA Billie Jean King National Tennis Center on September 07, 2026 in the Flushing neighborhood of the Queens borough of New York City. (Photo by Matthew Stockman/Getty Images)

NEW YORK, NEW YORK - SEPTEMBER 07: Learner Tien of the United States reacts after being defeated by Karen Khachanov during their Men's Singles Fourth Round match on Day Nine of the 2026 US Open at USTA Billie Jean King National Tennis Center on September 07, 2026 in the Flushing neighborhood of the Queens borough of New York City. (Photo by Matthew Stockman/Getty Images)

Netherlands' Botic van de Zandschulp returns the ball to France's Arthur Gea during the men's singles round of 16 tennis match on day nine of the US Open tennis tournament at the USTA Billie Jean King National Tennis Center in New York City on September 7, 2026. (Photo by Leonardo MUNOZ / AFP via Getty Images)

Netherlands' Botic van de Zandschulp returns the ball to France's Arthur Gea during the men's singles round of 16 tennis match on day nine of the US Open tennis tournament at the USTA Billie Jean King National Tennis Center in New York City on September 7, 2026. (Photo by Leonardo MUNOZ / AFP via Getty Images)