It was held on outdoor hardcourts at the USTA Billie Jean King National Tennis Center in Flushing Meadows, New York City.

[5] Novak Djokovic was attempting to be the first man to complete a calendar Grand Slam in men's singles since Rod Laver in 1969, having won the men's singles tournaments at the 2021 Australian Open, French Open and Wimbledon, but unlike Alcott and de Groot, who also won the Olympic gold medal (Djokovic lost to Alexander Zverev in the semifinal for the gold medal match at the Olympics in 2021), he lost to Medvedev in the final.

[6] The United States Tennis Association allowed the return of spectators after the 2020 tournament was held behind closed doors due to the COVID-19 pandemic in New York.

Due to a surge in COVID-19 cases resulting from the delta variant of the virus, spectators had to present a negative COVID-19 test or proof of vaccination in order to be allowed to enter the grounds.

[7] The 2021 US Open was the 141st edition of the tournament and took place at the USTA Billie Jean King National Tennis Center in Flushing Meadows–Corona Park of Queens in New York City, United States.