Spain's Roberto Bautista Agut has been ruled out of the Davis Cup after suffering an abdominal injury in training and will be replaced by Albert Ramos, the Spanish tennis federation said.
World number 19 Bautista Agut, who helped Spain clinch the 2019 title against Canada in the inaugural edition of the revamped event, was the highest-ranked singles player in the team.
Ramos, 33, will join Pablo Carreno Busta, Feliciano Lopez, Marcel Granollers and 18-year-old Carlos Alcaraz, who will be making his Davis Cup debut.
Spain will also be without 20-times Grand Slam winner Rafa Nadal as he continues his recovery from a foot injury.
They begin the defence of their title against Ecuador in Madrid on Friday before taking on the Russian team on Saturday