An average of 4.6 million viewers watched four-time Olympic gold medallist and 23-time Grand Slam singles winner Williams lose 7-5, 6-7, 6-1 to Tomljanović.

It is widely expected to be the 40-year-old's last match after a glittering career which has led to her being considered by many as the best tennis player of all time.

Her third-round tie broke the previous record of 3.9 million viewers for a tennis match on ESPN, which belonged to the 2012 Wimbledon men's singles final between Switzerland's Roger Federer and Britain's Sir Andy Murray.

Williams' match against Tomljanović drew a peak of 6.9 million viewers on ESPN.

Her second-round victory against Anett Kontaveit of Estonia attracted an average of 3.6 million viewers.

The channel has reported a 101 per cent increase in viewing numbers from the first five days of the US Open compared to last year's tournament, averaging at 1.1 million across its networks.

This makes it the most viewed opening five days on record.

The American broadcaster took over exclusive broadcasting rights in the United States for the US Open in 2015, from CBS who had shown the Grand Slam since 1968.

ESPN also holds rights to the Australian Open and Wimbledon.

Williams has also broken social media and attendance records at her US Open farewell.

Twitter reported that she is the most-posted-about female athlete in its history, while her match against Tomljanović came on a day in which a record 72,039 fans attended matches at the Billie Jean King National Tennis Center, including 23,859 spectators for the night session at the Arthur Ashe Stadium.