Roger Federer paid tribute to his retiring rival Rafa Nadal on Tuesday, telling the Spaniard he challenged him like no other player and that he had made the tennis world proud during a glittering career lasting over two decades.

Nadal is part of the Spain side that will begin their Davis Cup campaign against the Netherlands later on Tuesday, with the injury-plagued 22-times Grand Slam champion set to call time on his career after the team competition in Malaga.

Federer, who was part of the “Big Three” of men’s tennis alongside Nadal and Novak Djokovic, posted a letter on X looking back at his rivalry with the 38-year-old.

“Let’s start with the obvious: you beat me - a lot. More than I managed to beat you. You challenged me in ways no one else could,” Federer said of Nadal, who edged their rivalry 24-16.

“On clay, it felt like I was stepping into your backyard, and you made me work harder than I ever thought I could just to hold my ground.

“You made me re-imagine my game - even going so far as to change the size of my racket head, hoping for any edge.”

Federer, who won 20 Grand Slam titles before retiring in 2022, also poked fun at Nadal’s courtside quirks.

“I’m not a very superstitious person, but you took it to the next level,” Federer added.

“All those rituals. Assembling your water bottles like toy soldiers in formation, fixing your hair, adjusting your underwear … all of it with the highest intensity.

“Secretly, I kind of loved the whole thing. Because it was so unique - it was so you. And you know what, Rafa, you made me enjoy the game even more.”

Nadal was by Federer’s side in the Swiss great’s final event when they played doubles for Team Europe at the Laver Cup in 2022, with images of the pair crying together going viral on social media.

“It meant everything to me that you were there by my side - not as my rival but as my doubles partner,” Federer added.

“Sharing the court with you that night, and sharing those tears, will forever be one of the most special moments of my career.”