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,

Roger Federer, Novak Djokovic and Andy Murray have shown up at the French Open to participate in a ceremony honoring 14-time tournament champion Rafael Nadal.

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