Roger Federer has published a long letter paying tribute to great rival Rafael Nadal ahead of the Spaniard’s retirement, saying: “Your old friend is always cheering for you.”

Nadal is bidding goodbye to tennis at the Davis Cup finals in Malaga this week, with Spain beginning their campaign against the Netherlands later on Tuesday. Federer and Nadal’s rivalry defined one of the greatest eras in the sport, with the pair locking horns 40 times between 2004 and 2019.

In the letter posted on social media, Federer wrote: “Vamos, Rafael Nadal! 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 racket head, hoping for any edge. And you know what, Rafa, you made me enjoy the game even more. OK, maybe not at first. After the 2004 Australian Open, I achieved the number-one ranking for the first time. I thought I was on top of the world.

“And I was – until two months later, when you walked on the court in Miami in your red sleeveless shirt, showing off those biceps, and you beat me convincingly.

“We were both at the start of our journey and it’s one we ended up taking together. Twenty years later, Rafa, I have to say: What an incredible run you’ve had. Including 14 French Opens – historic! You made Spain proud … you made the whole tennis world proud.”

Federer referenced Nadal’s famous rituals and the time his four children have spent at the 38-year-old’s tennis academies, adding: “I always worried my kids would come home playing tennis as lefties.”

They competed in nine grand slam finals, with Nadal winning six of them, but one of their most famous moments together came at Federer’s emotional farewell at the Laver Cup in London two years ago, when the pair were pictured crying and holding hands.

“It meant everything to me that you were there by my side – not as my rival but as my doubles partner,” said the Swiss. “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.”

Nadal was asked at a press conference on Monday about the possibility of Federer travelling to Malaga, with Novak Djokovic having already said he would come.

“I didn’t talk to Roger,” said Nadal. “I think Roger has a busy schedule. By the way, of course that’s going to be my last week on the professional tour, but I don’t think it’s going to be my last goodbye. So there’s going be other chances to do something.”