Denmark's Holger Rune withdrew from the upcoming Laver Cup after receiving treatment for a back injury.
Spain's Alejandro Davidovich Fokina replaced the World No. 4 on the roster for Team Europe.
"As I am in treatment with my back it's not possible for me to play Laver Cup next week," Rune, 20, posted Sunday on social media. "I would have loved to join the fight to get the trophy back to Europe and I will support my teammates from a distance."
The Laver Cup, pitting Team Europe against Team World, runs from Friday through Sunday in Vancouver, British Columbia.
Davidovich Fokina, 24, joins Stefanos Tsitsipas (Greece), Andrey Rublev (Russia), Casper Ruud (Norway), Hubert Hurkacz (Poland) and Gael Monfils (France) on a roster captained by Bjorn Borg.
"You play against the best players in the world at Laver Cup," Davidovich Fokina said. "I am excited to be a part of Team Europe, to share the court with other great players and to have them supporting you."
John McEnroe is the captain of Team World, featuring Americans Taylor Fritz, Frances Tiafoe, Tommy Paul and Ben Shelton along with Felix Auger-Aliassime (Canada) and Francisco Cerundolo (Argentina).
—Field Level Media