Frances Tiafoe has replaced John Isner in the Team World line-up for next week's Laver Cup in London.
Isner has failed to recover from the wrist injury that forced him to withdraw from the US Open ahead of his second-round match against Holger Rune.
Fellow American Tiafoe knocked out Rafael Nadal en route to reaching the semi-finals at Flushing Meadows, where he was beaten by tournament winner Carlos Alcaraz.
The 24-year-old, now at a career high of 19th in the ATP rankings, will take Isner's place at the O2 Arena as Team World aim to end Team Europe's run of four triumphs in a row.
Tiafoe previously took part in the tournament in 2017 and 2018, but has missed the past two editions.
Team World captain John McEnroe said: "I am thrilled to have Frances on the team.
"He's raised his game to a whole new level and has shown he can compete and win against the best players on Tour. He brings a positive energy that should help the entire team."
Tiafoe joins Felix Auger-Aliassime, Taylor Fritz, Diego Schwartzman, Alex de Minaur and Jack Sock on McEnroe's six-man team.
Team Europe, led by Bjorn Borg, is made up of Nadal, Novak Djokovic, Stefanos Tsitsipas, Casper Ruud, Roger Federer and Andy Murray.
The tournament is contested on an indoor hard court and runs for three days from September 23.