Dan Evans, who reached the fourth round here a year ago, is still serving a ban after his positive cocaine test, while Aljaz Bedene - who will play an eye-catching first-round match here against defending champion Roger Federer - has switched his nationality back to his native Slovenia.
A knee injury which has prevented Nadal from playing competitively since losing to David Goffin at the ATP Finals in November has restricted the 16-time major champion to just a pair of exhibition contests in Melbourne - a far cry from his run to the quarter-finals at the Brisbane International a year ago.
Nadal heads defending champion Roger Federer at the top of the men's seedings, with Simona Halep and Caroline Wozniacki seeded one and two in the women's competition.
He returned to action at a non-tour event - Kooyong Classic - and lost his first match there to Richard Gasquet on Tuesday, January 9.
Third seed Grigor Dimitrov or eighth seed Jack Sock are possible semi-final opponents for the 16-time Grand Slam victor.
Serena Williams will not defend the women's title having had her first child previous year but 2008 champion Maria Sharapova, who failed a drugs test at the tournament in 2016, is back unseeded after a ban and will face Germany's Tatjana Maria.
Stan Wawrinka, the 2014 victor, meets Ricardas Berankis, while fourth seed Alexander Zverev has been drawn against Thomas Fabbiano.
Federer once again anchors the last quarter.
What was more concerning, albeit in an exhibition, was his performance against retired 36-year-old Lleyton Hewitt in the semi-finals of the event - first to 10 points - having survived match points against the Australian.
Eight players retired from the first round at the All-England Club, including the opponents of Roger Federer and Novak Djokovic during the second sets of their matches on Centre Court.
Their replacement - a "lucky loser" from the qualifying tournament - will get the other 50 percent of the first-round prize money.
He beat Grigor Dimitrov in straight sets in the second round of the 2017 US Open.
Simply by turning up, they were eligible for prize money and avoided a fine.
It is those who have failed to make the trip Down Under - or those who have limped here carrying injuries - who are causing a stir and, as a result, both draws are supposed to be there for the taking by any young hopeful with a bit of a courage and a hefty forehand.
In a separate rule change created to get matches started more quickly, warm-up times will be strictly enforced.
The first Grand Slam of 2018 is just about here in the Australian Open from Melbourne.