When john mcEnroe is asked Rafael Nadal's about the rules at the australian open tennis clearly has a problem. 

unlike most sports, tennis relies on both players being fit and able to play. There are no substitutions, so if a player can't continue the match is over. While they can sometimes move the next match onto the court early in general a mid match retirement is a problem.

2. The winter olympics will begin at Friday, February 9 in pyeongchang