Rafael Nadal called time on his illustrious tennis career last year, but the Spaniard is still keen to compete against his former 'Big Four' rivals in another sport

"Roger Federer and Rafael Nadal are no longer active, which affects my motivation a bit. However, I would not be on the Tour without motivation. I would not play anymore and would put the racquet to rest. I still feel the desire to compete - it's always there.

At 37, Serbian tennis player Novak Djokovic addressed whether he has lost motivation to continue playing following the retirements of Roger Federer and Rafael Nadal.