The two, who between them have won 42 Grand Slam singles titles, joined forces in a doubles match for Federer's swansong at the Laver Cup in London.
Following the conclusion of that match, images of both players weeping during the post-match ceremony went viral.
“Someone I have admired, who I have rivalled and also I have shared many beautiful things on and off the court was leaving," Nadal told reporters ahead of an exhibition match in Argentina.
“In that sense, all those moments, those feelings you have before playing a final of a Grand Slam, of an important tournament, everything that was in the air before those matches. It was different from other matches.
“You know you’re not going to live that again and a part of my life left with him (when he retired). It was also the emotion of saying goodbye to someone who has been so important to our sport.”
The Spaniard is on an exhibition tour of South and Central America alongside Norwegian Casper Ruud (23).
