Eight-time Grand Slam winner Andrew Agassi feels Alexander Zverev and Nick Kyrgios are the most likely successors to the big four. Roger Federer, Rafael Nadal, Novak Djokovic and, to a lesser extent, Andy Murray have dominated tennis for well over a decade, winning the majority of Grand Slams during that period.
Murray is on the comeback trail after a long-term injury but the other three are still winning the biggest events, with Federer taking the Australian Open, Nadal triumphing at Roland Garros and Djokovic claiming the spoils at Wimbledon.
However, they cannot go on forever and Agassi feels that there are a couple of youngsters who can fill the void.
“I think Alex Zverev, or Sacha as they call him, is the guy to watch moving forward, but not right here and right now,” the American told Tennis365.
“A lot of people fear what will happen to tennis when Federer, Nadal and Djokovic are not playing anymore, but I would look at it in a more positive light. Maybe by the time these great players go, we will be ready for new guys to come in and give the sport a new look.
“Zverev is the one guy I believe can win a lot of big titles if he gets everything right.
“Kyrgios may be the greatest natural talent of the guys coming through now, but you have to wait and see if he can put it all together when it matters most.”