Boris Becker has warned his fellow tennis icons that their career shelf life may be limited in a generational changing of the guard.

The six-time Grand Slam champion who now comments for Eurosport said 22-time Grand Slam champions Novak Djokovic and Rafael Nadal should be looking over their shoulders at the advancing rivals.

The pair of over-35s are the last remaining elites from the Big 3 group, which began its dissolution with the September retirement of Swiss legend Roger Federer, victim of a knee injury he could not overcome at age 41.

But Becker, 55, who went through the same evolution during his own career, has wise words for the current duo.

“We are seeing the generational change at the moment,” he told Eurosport after Djokovic claimed a 10th Australian Open trophy at the weekend in straight sets over third-ranked Stefanos Tsitsipas, aged 24.

Becker was particularly concerned about Nadal, who exited in the Melbourne second round last month in yet another injury crisis.

“Roger Federer has already retired and Rafael Nadal, for me, is one step away from doing it.”

Nadal will now focus his season on winning an historic 15th title at Roland Garros.

“Rafa will play in Paris, but later I see a question mark about that. I think if Novak manages to win the 23rd Grand Slam by turning 36 next year, then it might be a matter of time before he decides to retire,” Becker said.

The German gives Djokovic a few more seasons.“Novak is 35 years old and he knows that at 40 he will not be able to reach the level he is at now.

“It will be interesting to see what level he maintains after his performance at the Australian Open.

“In Paris and Wimbledon he will have to do different things if he wants to win. Success is his life’s dream, he wants to become the most successful player in history.”