Roger Federer has credited his rivalry with Rafael Nadal for making him as good a player as he could be.
The 20-time grand slam champion won an unprecedented fifth Laureus World Sportsman of the Year award on Wednesday and continues to perform at the highest level at the age of 36.
Federer and Nadal have contested nine major finals over the course of their careers, with the Spaniard winning six of those matches.
The most recent final clash between the pair - at last year's Australian Open - went Federer's way, earning the veteran his first grand slam title in five years and the first of three in the space of 12 months.
The Swiss star and Nadal, along with Novak Djokovic and Andy Murray, have headlined a golden era for men's tennis, and the six-time ATP Finals winner believes that level of competition has been of huge benefit to his game.
"Well Rafa has had such a big impact in my sporting career," Federer told Perform.
"When I came on to the stage I was trying to find my way to world number one. Later on he finally arrived in a big way because he was one of the best teenagers of all time, besides Bjorn Borg.
"In the beginning you try to fight it off until you realise he's a legitimate rival and he's better than me on clay. It's one thing you really need to dig deep to find solutions.
"For that I'm forever thankful to Rafa, he definitely made me a better player. Today I can also call him a friend.
"We still push each other on after all these years. I think that's why last year was so special."