Roger Federer and Rafael Nadal own an unforgettable collection of on-court contests - including nine Grand Slam finals - and a healthy store of mutual off-court respect for each other.

"I saw him grow, right in front of my eyes,” Federer said in an interview with last year. “I always feel like he’s one of the guys from tennis - players - that I could call up and, if I told him something, it would be a secret between the two of us. And I appreciate that we were able to build a relationship like that.”

READ: Nadal insists Federer Slam record not on his mind

Each has played more matches against Novak Djokovic, who leads his head-to-head series against the other members of the Big Three.

Yet it is Roger vs Rafa that seems to be the rivalry that stands above others. Perhaps because they’re currently Nos. 1-2 for most men’s Grand Slam titles. Or perhaps because of their epic 2008 final at Wimbledon, the tournament supposed to be happening now but canceled because of the coronavirus pandemic.

READ: Novak Djokovic: 'Big Three' rivalry great promotion for tennis

The dynamic between Federer, 38, and Nadal, 34, has shifted.

"We went in phases a little bit. In the beginning, he was so extremely shy and he was so - how do you say? - like, looking up to me, that he just said, ‘Whatever you say, Roger, I agree with you. Because you’re so important to the game. And I know you want the right thing,’” Federer said. “And over time, he became himself, the dominant player he became, and he started to build his own strong character. ... And then, of course, the rivalry started building.”