Wimbledon semi-finals: Will Jannik Sinner halt Novak Djokovic's potential farewell tour or will unthinkable happen to Italian again?

Novak Djokovic, 39, and world number one Jannik Sinner are set to meet in a heavyweight Wimbledon semi-final on Friday. Djokovic, a 23-time Grand Slam champion, has shown signs of fatigue in his last three matches at this year's tournament but has managed to grind out victories each time. Sinner, meanwhile, will need to manage heat-related issues if he is to perform at his best against the experienced Serb.