Andy Murray is primed for a comeback while Roger Federer and Novak Djokovic are looking for their seventh Australian Open titles.
Both have six titles, and are seeking to break a three-way tie for the most victories with Australia's Roy Emerson.
In the men's draw, world number one Novak Djokovic will start his drive to make history against a yet-to-be-decided qualifier and could meet France's Jo-Wilfried Tsonga in the second round.
"Osaka shines" The 21-year-old Osaka backed up her US Open win by riding a wave of fanatical home support to reach the final of the Pan-Pacific Open in Tokyo without dropping a set.
He retired in the quarter-finals against Marin Cilic a year ago in Melbourne and suffered yet another knee injury that forced him out of the US Open semi-finals before ankle surgery in November.
But McEnroe said Williams looked good and appeared to be in a great state of mind during last week's Hopman Cup in Perth.
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 exhausted of Federer winning everything. "It means so much to me". Wozniacki proved she can still compete by winning in Beijing in October but whether she can cope with the gruelling two-week slog of a Grand Slam remains to be seen, and she was bundled out of the Auckland Classic last week in round two.
Khachanov, 22, is seeded 10th at the tournament.
Two of the older generation who have shown they do have that ability - Britain's Andy Murray and Switzerland's Stan Wawrinka - could be unsafe floaters in the draw. It's a far cry from when Osaka came to Melbourne Park previous year as an unknown ranked 68. "Coming back as defending champion, it's something I always dreamed of", she said.
When it comes to Williams, who is seeking a record-equalling 24th Grand Slam singles title at the Australian Open, Evert believes it is her remarkable journey from the hardscrabble courts in Compton where she learned the game to the top of the tennis world that will be remembered most.
Williams reached the Wimbledon and US Open finals after her return a year ago but lost both, leaving her one short of Australian Margaret Court's tally of major singles titles.
Serena Williams, the 16th seed, will take on Tatjana Maria in her first match of the tournament.
The Romanian broke her major duck at the French Open in June last year and finished the season at number one for the second consecutive year. He expects her to be in the title mix going forward.
The 28-year-old Dane insists she can manage the debilitating auto-immune condition, which sometimes leaves her so exhausted she cannot raise her arms above her head.
Kerber beat Wiliams in the Wimbledon final to become the first German woman to win the grass court title since Steffi Graf in 1996.
Also in the mix is the popular Osaka, who stunned Williams in NY.