Bianca Andreescu, incidentally, the young Canadian who won so many hearts in Auckland, is also in Osaka's draw and the pair could meet in the third round if the hard-hitting Andreescu goes on another run in Melbourne.
Both Williams and Osaka are drawn away from Angelique Kerber, Julia Goerges, Sloane Stephens, defending champion Caroline Wozniacki, Maria Sharapova and Petra Kvitova, upcoming stars like Australia's great hope, Ashleigh Barty, plus Jelena Ostapenko and Aryna Sabalenka. The women's competition looks far more open and interesting than the men's, where Novak Djokovic is firm favourite.
Osaka, still only 21, has been patchy since her US Open win. That could simply be a common ailing: the season after a breakthrough win can be trying for young players. They burst into the spotlight, dazzle — but then have difficulty regaining that level. "Second season syndrome" is no fanciful concept.
Ostapenko, who broke through with her French Open win in 2017, is a good example. Her aggressive strokes seemed set to carry her to the top of the world but a less impressive 2018 saw her slip to 22 in the world ... watch out for a revival this year.
Osaka, meanwhile, lost in just over an hour this week in Brisbane's lead-up tournament to Ukraine's Lesia Turenko and afterwards admitted to "sulking" because she wasn't playing well. She later posted a tweet saying: "Had the worst attitude on court today. Sorry to anyone who watched. I keep telling myself to be more mature but it seems it'll take a while."
How cute is that? Not only cute but more self-aware and mature than Williams was in her US Open rant at umpire Carlos Ramos, an episode when Serena was anything but serene.
She too was not playing well; the umpire's decision to penalise her for being coached from the stands, for racquet abuse and calling him a "thief" set her off. She produced a tirade of accusations and tears, turning the whole episode into a gender issue by calling the umpire sexist and maintaining male players were never punished the same way.
Maybe that is mostly so — but it was a side issue. Anyone who saw the genesis of the meltdown could see it had little to do with gender. Her red herring was taken up by many, mostly female, protagonists to the extent that any male questioning Williams' behaviour became a part of the conspiracy. It was exacerbated by a (male) Aussie cartoonist whose caricature of Serena's tantrums was seen by everyone — except maybe himself — as racist.
But this was an open and shut case of bad behaviour unbecoming of the greatest player women's tennis has seen. It was unprofessional and disturbing for anyone who follows top-level sport and the mores that apply there. You can care deeply, even dramatically protest but, in the end, you take your lumps and salute the winner, no matter how much it hurts and how unfair the gods of tennis might have been.
Williams' actions ignited the partisan US crowd and they booed through the victory ceremony until Williams belatedly realised how all this appeared and attempted, unconvincingly, to comfort the younger woman.
What should have been Osaka's crowning moment saw her shunted into the background, a visit to victory which attained only victim status and brought her close to tears. A national poll in the UK later voted Osaka the most unfairly treated person in sport in 2018.
So I have two contradictory wishes for this tennis season and Australia Open: first, that Williams wins the grand slam tournaments she needs to underline what she clearly is — the best ever.
But I also hope Osaka conquers second season syndrome and wins another slam tournament in which she can be properly feted and grows into the kind of player who can overcome everything — everything — Serena Williams can throw at her.
