LONDON • Andy Murray finally voiced the unthinkable when he said on Saturday that tennis' Big Four - the elite club which he will captain for as long as he can hold Novak Djokovic at bay - could be without its founding members, Roger Federer and Rafael Nadal, within 12 months.
"I think next year will be interesting," the new world No. 1 said on the eve of the ATP World Tour Finals at the O2 Arena in Greenwich.
He begins his campaign against Marin Cilic of Croatia today.
"That will be the time to sort of tell whether it's done and that era is past," he added.
Federer, who dropped out of the top 10 for the first time in 14 years this month, and Nadal, who, like the Swiss, is absent because of injury.
They have struggled to stay in touch with Murray and Djokovic, who started his campaign with a 6-7 (10-12), 6-0, 6-2 win over Dominic Thiem.
New world No. 1 Andy Murray's unbeaten run going into his ATP World Tour Finals opener today.
And, when the Serb's run of 123 weeks as world No. 1 came to an end in Paris last weekend, the story shifted dramatically again.
Murray, who has been thrust to the top of the mountain against most expectations but who has earned the honour in the course of an unbeaten run of 19 matches, made his prediction with a sense of regret rather than celebration.
He acknowledges that Federer and Nadal have been probably the two best players in the history of the game and he knows that, when fit and in form, they demand total respect.
But, at 35 and 30 respectively, they have been unable to avoid the inevitable drag of physical decline.
The sharpness of hand and eye is ever so slightly dulled, the flexibility not what it was. The muscles and bones ache more deeply.
The passion? Even Djokovic, the sport's iron man, admits that comes under pressure too. But it all starts with the moving parts.
"When somebody is not playing for six months like Roger," Murray said, "then they can't maintain their ranking and they are not competing for the biggest events."
Nadal, just when he was starting to play better, had suffered a wrist issue and that has set him back.
The absence of Federer and Nadal is "strange indeed," said Paul Annacone, Federer's former coach.
"For a long time, we've wondered when this era will end. Maybe this is the start of it. I hope not. Roger and Rafa have been the cornerstones of greatness for so long, it's shocking to the system when they are not there."
The duo were together last month for the opening of Nadal's academy in Majorca, Spain, and both are preparing to return next year.
"Federer and Nadal have become global sports icons rather than just tennis stars," Chris Kermode, executive chairman and president of the ATP, said. "And of course there will be a time when their careers will come to an end, and they will be missed.
"But, having said that, no player is bigger than the sport itself, and men's tennis has had an almost uncanny ability to consistently produce global stars that do transcend the sport. And Roger and Rafa aren't done yet."
The main battlefield for a little while has featured three players: Murray, Djokovic and Wawrinka. Form suggests that is the way it will play out on the banks of the Thames this week.
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