The Big Four may still rule the tennis world, but their fitness is starting to give out and a crowd of young guns are waiting in the wings to take their places.
The Big Four are Roger Federer. Rafael Nadal. Novak Djokovic and Andy Murray.
These superstars have dominated the grand slams and tennis circuits for a decade or more.
Federer first won Wimbledon in 2003.
But creaking limbs and aching muscles have forced them all into recent lay-offs.
And although they have returned fitter and stronger to take all four of the most recent grand slam titles, time is catching up with them.
So, who are the new kids on the tennis block?
A host of next generation stars aged 21 or younger are intent on taking their shot at greatness and to follow the Big Four into the annals of tennis.
Three of them are already ranked highly in the game.
- Alex Zverev is a 20-year-old German hungry for success on the courts. He is currently ranked 12th in the world. Last year, he beat Federer and US Open champion Stan Wawrinka.
- Austrian Dominic Thiem ranks 8th in the world and critics and coaches rate him as one of the most gifted players of his generation. He reached the final of the French Open last year and is starting to pile ATP circuit titles. He has beaten Nadal and Djokovic.
- Canadian Milos Raonic is already a well-known tennis star at the age of 26. Has ranked as high as the world number three after reaching the finals at Wimbledon in 2016.
Ladies in waiting
For women, as the reigns of the Williams sisters come to an end, Elina Svitolina and Ana Konjuh are waiting to fill their shoes.
Ranked third in the world, Svitolina won the last Malaysian Open, beating Eugenie Bouchard. Svitolina comes from The Ukraine and is aged 23. She is waiting to face France’s Caroline Garcia in the quarter final of the China Open.
Konjuh reached the quarter finals of the US Open – the youngest player to do so for a decade. The Croatian is aged 19 and still has plenty of time to fill her potential.