Roger Federer pens emotional 584-word letter to Rafael Nadal as Spaniard retires

has paid tribute to by posting a lengthy farewell message on social media ahead of the Spaniard's impending retirement. He will bring the curtain down on his glittering career after representing Spain in the Davis Cup Finals.

It will certainly be an emotional week for Nadal, who will become the third member of the Big Four to hang up his racket for good. Federer, who retired at the Laver Cup two years ago, sent a heartfelt message to his former rival ahead of Spain's opening match.

Taking to , the Swiss icon wrote: "As you get ready to graduate from tennis, I've got a few things to share before I maybe get emotional. 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. 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 reimagine my game, even going so far as to change the size of my racquet head, hoping for any edge. I'm not a very superstitious person, but you took it to the next level. Your whole process. 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."

Federer went on to acknowledge Nadal's incredible trophy haul before reminiscing on their years battling each other on the court.

"Rafa, I have to say: what an incredible run you've had," he added. "Including 14 French Opens, historic! You made Spain proud... you made the whole tennis world proud.

"I keep thinking about the memories we've shared. Promoting the sport together. Playing that match on half-grass, half-clay. Breaking the all-time attendance record by playing in front of more than 50,000 fans in Cape Town, South Africa.

"Always cracking each other up. Wearing each other out on the court and then, sometimes, almost literally having to hold each other up during trophy ceremonies."

Federer also thanked Nadal for involving him in the launch of the Academy and allowing his children to train there. He finished his message by looking back at his own retirement at the Laver Cup, where they played doubles together.

"It meant everything to me that you were there by my side, not as my rival but as my doubles partner," wrote Federer. "Sharing the court with you that night, and sharing those tears, will forever be one of the most special moments of my career.

"Rafa, I know you're focused on the last stretch of your epic career. We will talk when it's done. For now, I just want to congratulate your family and team, who all played a massive role in your success.

"And I want you to know that your old friend is always cheering for you, and will be cheering just as loud for everything you do next. Rafa that! Best always, your fan, Roger."