As his tennis contemporaries continue to head off into retirement, Novak Djokovic is being faced with the reality that his time on the professional courts, too, will come to an end.  Ahead of his first-round matchup with American Mackenzie McDonald on Tuesday at the French Open,

Seeing Nadal, Federer and Murray all retire in the last few years has prompted Djokovic to think more about his own mortality.

Novak Djokovic revealed that retirement was on his mind while making an appearance honoring former rival Rafael Nadal at Roland-Garros on Sunday.