The replacement news comes in light of Isner fracturing his wrist prior to his second-round match at Flushing Meadows and pulling out of the tournament prematurely.
Tiafoe made history in New York last week, becoming the first black man since Arthur Ashe in 1972 to reach the semifinals of the US Open. After a victory over Rafael Nadal in the fourth round and Andrey Rublev in the quarterfinals, the American fell to eventual champion Carlos Alcaraz in the penultimate stage.
Former World No.1 John McEnroe, Team World's captain for the competition, was chuffed to have Tiafoe in his squad, remarking that the World No. 19 has raised his game to a "whole new level" this year. Having seen the 24-year-old go toe-to-toe against the very best players in the world, McEnroe was confident that he would be a valuable addition to his squad.
“I am thrilled to have Frances Tiafoe on the team,” McEnroe said in the press release. “He has raised his game to a whole new level and has shown that he can compete and win against the best players on Tour. Plus, he brings a positive energy that should help the entire team.”