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NEW YORK, NEW YORK - SEPTEMBER 02: Alexander Bublik of Kazakhstan returns the ball against Jack Sock of the United States during his Men's Singles second round match on Day Four of the 2021 US Open at USTA Billie Jean King National Tennis Center on September 02, 2021 in New York City. (Photo by Elsa/Getty Images)

NEW YORK, NEW YORK - SEPTEMBER 02: Alexander Bublik of Kazakhstan returns the ball against Jack Sock of the United States during his Men's Singles second round match on Day Four of the 2021 US Open at USTA Billie Jean King National Tennis Center on September 02, 2021 in New York City. (Photo by Elsa/Getty Images)