(CNN) - Is there anyone out there who can knock Roger Federer off his perch in Australia?
The 37-year-old started the year on the right foot, winning the Hopman Cup for the second straight time alongside Switzerland teammate Belinda Bencic. It was the perfect warmup on his way to defending -- for the sixth time -- his Australian Open title.
Despite his advancing years, Federer is champing at the bit to enhance his record of 20 grand slam titles and extend the run of dominance that an elite group known as the Big Four have shared for well over a decade.
Between them, Federer, Rafael Nadal and Novak Djokovic have won a staggering 51 of the 62 grand slams since the 2003 edition of Wimbledon.
Last year saw no sign of an end to their reign -- the trio shared the 2018 crop of grand slams.
Britain's Andy Murray, who announced his impending retirement from the sport Friday, is unseeded for the opening major of the year but rounds out the group. He has three grand slam trophies to his name, along with a respectable degree of tour success.
"Am I confident? I dunno!" the Swiss master Federer told CNN's Christina MacFarlane before the start of the Open on Monday.
"I've been training really well, I've had another great season this year, still happy playing and I won the last two Australian Open editions so yeah, I definitely should be going in there with confidence."
Despite his groaning trophy cabinet, Federer -- widely considered the greatest male tennis player of all time -- has dropped down the pecking order in recent years, with both Serbia's Djokovic and Spain's Nadal currently ahead of him in the world rankings.
Djokovic in particular looks set to continue to dominate the sport for a while yet.
The Serb, who ended a lull to win the last two of the four majors in 2018, looks set to be an irresistible force again this year. With a record-equaling six Australian Open titles under his belt, he is at least as likely a winner in Melbourne as his longtime friend and rival Federer.
The Serb, current number one in the ATP rankings, is the tournament top seed.
"Djokovic has had great success in Australia, he's won it six times, and the way he finished last year it's hard not to say it'll be him," tennis legend and broadcaster John McEnroe told journalists.
"Federer has positioned himself to have a good run. It's hard to pick."
So where are the youngsters?
Incredibly, there has yet to be a men's grand slam winner who was born in the 1990s. The youngest, Marin Cilic, who won the 2014 US Open, was born in September 1988.
McEnroe says it's increasingly hard for younger players to break down their older opponents' fast and physical games over the course of a grueling tournament.
"The game has become more physical and the ball has been struck faster -- it's just become more difficult for a young kid to be able to stand up to that for seven matches," the seven-times grand slam champion told journalists in Melbourne.
So it could be up to another veteran to break the foursome's grip on the tour.
By the numbers, Juan Martin del Potro (No. 5) is best placed, although he won't appear in Melbourne due to injury. Or Cilic could summon up the grit and resolve he showed to beat Kei Nishikori in straight sets at Flushing Meadows in 2014.
Kevin Anderson, runner-up to Djokovic at last year's Wimbledon, could also present a challenge.
Still, McEnroe feels a corner is about to be turned.
"I believe this year will be the year that you are going to see one of these young kids break through," he said.
Many pundits, McEnroe included, believe Germany's Alexander Zverev -- Federer's Hopman Cup final opponent -- is the most likely candidate to step up and snatch a Slam trophy.
After defeating Djokovic to win the ATP Tour Finals in London in November, beating the No. 1 and No. 2 seeds on consecutive days, the German is growing in confidence, technique and ability -- and in 2019 the world No. 4 is a good prospect to pick up his first Slam trophy.
He's joined by a host of other strong claimants in their 20s, including Austria's Dominic Thiem, Greece's Stefanos Tsitsipas, Australian bad boy Nick Kyrgios, the Russian duo of Karen Khachanov and Daniil Medvedev, and Britain's Kyle Edmund.
"The door is open: if you look at the rankings, you have a lot of players positioned to make a big breakthrough," McEnroe said.
"I believe there will be a changing of the guard this year. Whether it's Zverev, or one of the others like Khachanov or Tsitsipas, you're going to see them do something big."
But for that to happen, and for the world to embrace a new generation of superstars, the old guard will first have to step aside.
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