Del Potro's letter to Djokovic: "A sincere friendship that will last forever. I love you."

Just three days after ending his career with a magnificent exhibition match against Novak Djokovic in Buenos Aires, Juan Martin Del Potro addressed his final opponent.

In a superb letter, the Argentine addressed Djokovic, thanking him profusely (see full version below): "I am eternally grateful to you, Charly, Mark and your whole team, for having been available in every detail, in every need. You understood the situation I was in, and you were the best partner, on and off the pitch, to say goodbye that I could never have imagined in my best dreams.

Your presence not only made this event unforgettable for me and my family, it transcended tennis. A whole country was able to appreciate you and be moved by you, and it's clear that you're not only the greatest in history in sport, but also in life.

Argentina loves you, and we are eternally grateful for the show, the generosity and the dedication you have shown to make this day perfect.

I have the feeling that all this was born of something very special: a sincere friendship that will last forever. I love you very much, my friend.
Thank you so much and see you soon."