Novak Djokovic and Rogerer Federer loom over Melbourne Park for the year's opening Grand Slam as favourites for the Australian Open as questions remain as to whether one of Generation Next could finally end their stranglehold.
The Serbian world number one and his Swiss opponent have won eight of the nine titles on Rod Laver Arena since 2010 and 11 of the last 13 on the bright blue courts in central Melbourne.
Both have six titles each, and are seeking to break a three-way tie for the most victories with Australia's Roy Emerson.
While Federer has won the tournament for the last two years -- with the 2017 victory at the age of 35 a surprising return after knee surgery in 2016 -- Djokovic's history in Australia and rediscovery of his form midway through last year means the world number one will be the man to beat.
The 31-year-old went into a bewildering slump in mid-2016 that only ended when he won Wimbledon last year before he went on to claim his third U.S. Open crown and move to 14 Grand Slam titles, three behind Rafael Nadal.
The Spanish world number two, however, is battling another leg injury that forced him out of the Brisbane International last week.
While he told local media on Tuesday that he did not feel any pain from his thigh strain, it is apparent that hard courts are putting undue stress on the 32-year-old's body.
He retired in the quarter-finals against Marin Cilic last year in Melbourne and suffered yet another knee injury that forced him out of the US Open semi-finals at Flushing Meadows before he had ankle surgery in November.
Federer, however, continues to defy the odds at 37 and prepared for his title defence with some convincing performances in the Hopman Cup in Perth last week.
The 20-time Grand Slam winner's victories over Greece's world number 15 Stefanos Tsitsipas and world number four Alexander Zverev prompted the German to playfully quip that he was tired of Federer winning everything.
"I mean, you're 30-whatever. Why? Just why?," Zverev asked jokingly of Federer at the Hopman Cup trophy presentation.
The 21-year-old Zverev appears the most likely of the younger generation of players hoping to end the world's top three's domination of Grand Slams, having beaten Federer and Djokovic at the ATP Tour Finals in London last November.
While others in 'Generation Next' like Austria's Dominic Thiem and the 22-year-old Russians Karen Khachanov and Daniil Medvedev could cause upsets, it is debateable whether they have can win seven matches over 14 days.
Two of the older generation who have shown they do have that ability -- Britain's Andy Murray and Switzerland's Stanislas Wawrinka -- could be dangerous floaters in the draw as they make their way back from injury-plagued seasons.
Murray, a five-time finalist at Melbourne Park, spent most of last year recuperating from hip surgery and looked rusty last week in Brisbane but declared himself pain free.
Wawrinka, the 2014 champion, is also coming back from knee surgery and a back injury in the second half of 2018, but typically flies under the radar through Grand Slams and unlikely to have any pressure, which makes him more lethal.
The women's draw looks more open even with Serena Williams, the most dominant force in the sport, back chasing a 24th Grand Slam singles title to tie Margaret Court's all-time record.
The American was eight weeks pregnant when she won her 23rd title at Melbourne Park in 2017 and returned to action last year where she reached finals at Wimbledon and the US Open.
Williams, who played at the Hopman Cup in Perth, enters the year's first grand slam ranked 16th but she still remains the favourite in Melbourne even if she lost to Naomi Osaka in the Flushing Meadows final.
World number one Simona Halep, with a massive burden off her shoulders, will hope to go one better this year having lost the 2018 final to Caroline Wozniacki.
The Romanian, who lost to Ash Barty in the second round of the Sydney International on Wednesday, broke her grand slam duck at the French Open in June last year and finished the season at number one for the second consecutive year.
Halep, who is without a coach since Australian Darren Cahill left for family reasons, will expect her back to hold up in competition after a herniated disk curtailed her 2018 season.
Wozniacki also has a question mark over her fitness after the 28-year-old Dane revealed her battle with rheumatoid arthritis last October but has since claimed that she has learnt to live with it.
A second Australian Open title will be a perfect birthday gift for world number two Angelique Kerber, who turns 31 in the first week of the tournament.
Kerber beat Wiliams in the Wimbledon final to become the first German woman to win the grass court title since Steffi Graf in 1996.
She has looked sharp at the Hopman Cup and maintained her 100 percent singles record even though Germany lost to Federer's Switzerland in the final.
Kerber has replaced coach Wim Fissette with 2003 Australian Open finalist Rainer Schuettler and a more aggressive approach could be the hallmark of the new partnership.
Also in the mix is the popular Osaka, who stunned Williams in New York.
The 21-year-old Japanese, however, had an inconsistent build up to the year's first grand slam.
Osaka suffered a straight set loss to Lesia Tsurenko in the semi-final of the Brisbane International and withdrew from the Sydney International in frustration.
