Tennis is currently dominated by the 'big 4' players - Roger Federer, Rafael Nadal, Novak Djokovic and Andy Murray. However, with all of them now in their 30s, the sport must soon look ahead to the future. This article examines how tennis may fare once the big 4 retire. It suggests that the quality of the sport will diminish as the big 4's aura and achievements will be hard to replicate. Young players must now step up and take their place in order for the sport to survive. It is clear that tennis must soon look to the post-big 4 era, in order to ensure a bright and successful future.