One of the greatest tennis, and indeed, sporting rivalries of all time is undoubtedly Roger Federer vs Rafael Nadal.
A recent surge in form from the two has brought that rivalry into the spotlight once more, and with Nadal winning the US Open, Federer has been talking about their relationship after many years of fighting it out on court.
Federer said: "But Rafa [Nadal], he's been such a wonderful champion and a good friend of mine on the tour, one of my big rivals for life, that it's just nice to be able to spend some time with him and support him."
After so many tough and legendary matches between the two, it is clear the massive respect that Federer has for the Spaniard.
That's even more present in the aftermath of Rafa taking his third US Open title and returning to world number 1 in the ATP rankings.
Federer, himself a five time US Open champion, also spoke about how he saw their rivalry developing in the future.
He said: "If I can help him, great. If he can help me, even better.
"Finally, after all these years, I get a chance to actually support his forehand, his aggressive play, his everything, his fighting spirit. Everything before was always like, ahh, another forehand and another fighter."
Bringing two very different styles to the court, with Nadal’s power and energy, against Federer’s precision and finesse, the two have rightly put themselves into discussions about the greatest players of all-time.
Undoubtedly, with the current absence of Andy Murray through injury and the loss of form of Novak Djokovic, this renaissance period for two of the all-time greats will be welcomed by tennis fans and neutrals alike.
And, with Federer talking about the change in relationship of the two over the years, the thought of both men trying to improve each other further will be a frightening prospect for the rest of the players on the ATP tour.