Djokovic's latest triumph at the U.S. Open saw him equal Margaret Court's record of major singles titles.

"It's up to the young guys to be pushing Novak and looking to overtake him. It doesn't look like that's close to happening," Murray told the BBC on Monday.

"He proved that he's the best player in the world again yesterday and like I said it's up to the youngsters to improve enough to take him."

The Serb, one of the 'Big Three' with Rafael Nadal and Roger Federer who dominated men's tennis for the past two decades, said he had no plans to retire.

"Novak's longevity has been the greatest. He's played at this level for such a long time now," said Britain's Murray, who has won three Grand Slams.

In July, 20-year-old Carlos Alcaraz ended Djokovic's Wimbledon reign after the Serbian had won four titles in a row at the All England Club. However, Murray believes the wrong conclusions were drawn from the Spaniard's victory.

"I said that after Wimbledon, everyone was saying it was a changing of the guard, but it wasn't for me," he added.

"Physically, motivation, whether someone like Alcaraz improves... He's an amazing player, Alcaraz, he's brilliant, but to do what Novak is doing on a consistent basis is different."

World number one Djokovic will next travel to Valencia and join the Serbia team for their Davis Cup Finals group stage ties with South Korea, Spain and Czech Republic.