Electronic line-calling will be used on all competition courts at this year's US Open.
The technology was utilised at the Grand Slam tournament in 2020, with the exception of Arthur Ashe Stadium and Louis Armstrong Stadium.
Top seed Novak Djokovic was playing on Arthur Ashe last year when he was disqualified after accidentally hitting a line judge in the throat with a ball struck in annoyance during his fourth-round match against Spain's Pablo Carreno Busta.
The United States Tennis Association's decision to extend the usage of the Hawk-Eye Live system will prevent a repeat of that controversial incident due to no line judges being on court.
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The USTA said in a statement that seven of the nine ATP and WTA tournaments on the US swing would use the technology on all competition courts in 2021.
"The USTA implemented electronic line-calling for the 2020 Western & Southern Open and US Open on all courts except Arthur Ashe and Louis Armstrong Stadiums," the governing body added.
"In total, Hawk-Eye Live made upwards of 314,000 calls during the two tournaments."
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The US Open is scheduled to take place from August 30 to September 12.
The 2021 Australian Open was the first major to be played entirely without line judges.
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