NEW YORK, NEW YORK - AUGUST 31: Matteo Berrettini of Italy returns a shot during his Men's Singles third round match against Alexei Popyrin of Australia on day six of the 2019 US Open at the USTA Billie Jean King National Tennis Center on August 31, 2019 in Queens borough of New York City. (Photo by Clive Brunskill/Getty Images)
NEW YORK, NEW YORK - AUGUST 31: Matteo Berrettini of Italy returns a shot during his Men's Singles third round match against Alexei Popyrin of Australia on day six of the 2019 US Open at the USTA Billie Jean King National Tennis Center on August 31, 2019 in Queens borough of New York City. (Photo by Clive Brunskill/Getty Images)
NEW YORK, NEW YORK - AUGUST 31: Matteo Berrettini of Italy returns a shot during his Men's Singles third round match against Alexei Popyrin of Australia on day six of the 2019 US Open at the USTA Billie Jean King National Tennis Center on August 31, 2019 in Queens borough of New York City. (Photo by Clive Brunskill/Getty Images)
NEW YORK, NEW YORK - AUGUST 31: Matteo Berrettini of Italy returns a shot during his Men's Singles third round match against Alexei Popyrin of Australia on day six of the 2019 US Open at the USTA Billie Jean King National Tennis Center on August 31, 2019 in Queens borough of New York City. (Photo by Clive Brunskill/Getty Images)
NEW YORK, NEW YORK - AUGUST 31: Alexei Popyrin of Australia runs at the net during his Men's Singles third round match against Matteo Berrettini of Italy on day six of the 2019 US Open at the USTA Billie Jean King National Tennis Center on August 31, 2019 in Queens borough of New York City. (Photo by Clive Brunskill/Getty Images)
NEW YORK, NEW YORK - AUGUST 31: Alexei Popyrin of Australia serves during his Men's Singles third round match against Matteo Berrettini of Italy on day six of the 2019 US Open at the USTA Billie Jean King National Tennis Center on August 31, 2019 in Queens borough of New York City. (Photo by Clive Brunskill/Getty Images)
NEW YORK, NEW YORK - AUGUST 31: Matteo Berrettini of Italy returns a shot during his Men's Singles third round match against Alexei Popyrin of Australia on day six of the 2019 US Open at the USTA Billie Jean King National Tennis Center on August 31, 2019 in Queens borough of New York City. (Photo by Clive Brunskill/Getty Images)
NEW YORK, NEW YORK - AUGUST 31: Alexei Popyrin of Australia returns a shot during his Men's Singles third round match against Matteo Berrettini of Italy on day six of the 2019 US Open at the USTA Billie Jean King National Tennis Center on August 31, 2019 in Queens borough of New York City. (Photo by Clive Brunskill/Getty Images)
NEW YORK, NEW YORK - AUGUST 31: Alexei Popyrin of Australia returns a shot during his Men's Singles third round match against Matteo Berrettini of Italy on day six of the 2019 US Open at the USTA Billie Jean King National Tennis Center on August 31, 2019 in Queens borough of New York City. (Photo by Clive Brunskill/Getty Images)
NEW YORK, NEW YORK - AUGUST 31: Matteo Berrettini of Italy returns a shot during his Men's Singles third round match against Alexei Popyrin of Australia on day six of the 2019 US Open at the USTA Billie Jean King National Tennis Center on August 31, 2019 in Queens borough of New York City. (Photo by Clive Brunskill/Getty Images)