The Spanish 22nd seed defeated Novak Djokovic on his way to the title in Doha last week while concerns about Murray’s fitness grew as he struggled through a practice match against Serbia’s world No 1 at Melbourne Park on Thursday.
Yorkshire’s Kyle Edmund, back at the scene of his semi-final appearance 12 months ago, was also given a difficult opener against former top-10 stalwart Tomas Berdych, who is unseeded following injury.
Cameron Norrie goes into the tournament as Britain’s form man and he faces a rematch with American Taylor Fritz, who he defeated to reach the semi-finals of the ASB Classic in Auckland on Thursday.
Defending champion Roger Federer takes on Denis Istomin in round one and is in the same half of the draw as Rafael Nadal, who faces Australian James Duckworth.
Djokovic, who like Federer is bidding for a record seventh title in Melbourne, will play a qualifier in round one.
Federer has won the title the last two years and has an extra carrot having gone into the season on 99 career singles titles. One more here would see him follow Jimmy Connors as the only man in the Open era to hit three figures, as well as taking him past Djokovic and Roy Emerson at Melbourne Park.
He said: “Ninety-nine is already an incredible number. I could live happily ever after on 99. But being so close, I’ll give it a go. If it would happen defending this title, I would gladly accept it. Reaching 100 would be truly very special for me.”
All the active grand slam winners in the men’s game are over 30 and one of the most intriguing storylines will be whether the new generation can finally break the stranglehold.
Seven-time grand slam winner John McEnroe, whose best in Australia was a semi-final apearance in 1989, is convinced a changing of the guard will take place this year.
“I believe this year will be the year that you are going to see one of these young kids break through,” said McEnroe.
“The door is open, if you look at the rankings. You have (Alexander) Zverev at four, (Karen) Khachanov at 11, (Stefanos) Tsitipas is around that place in the rankings. You have (Denis) Shapavalov in the 20s – so you have a lot of players positioned to make a big breakthrough.”
In the women’s draw, Britain’s Johanna Konta begins her campaign against Australia’s Ajla Tomljanovic, who she lost to in Brisbane last week.
Konta is in a loaded top quarter of the draw that also includes world No 1 Simona Halep – who faces a rematch with her US Open conqueror Kaia Kanepi – Serena and Venus Williams, Garbine Mugurza and Karolina Pliskova.
Serena Williams, who is seeded 16th, faces fellow mother Tatjana Maria of Germany in her first competitive match since her tempestuous US Open final loss to Naomi Osaka.
Defending champion Caroline Wozniacki takes on Belgian Alison van Uytvanck in round one and could potentially meet 30th seed Maria Sharapova in the third round.
Wozniacki finally broke her grand slam duck 12 months ago but struggled through the rest of 2018 before revealing a diagnosis of rheumatoid arthritis.
British No 2 Heather Watson takes on 31st seed Petra Martic from Croatia while Katie Boulter, playing in her first slam main draw outside of Wimbledon, meets Russian Ekaterina Makarova.
Veteran Andreas Seppi knocked out top seed Stefanos Tsitsipas to reach the last four of the Sydney International.
The 34-year-old Italian saved six of seven break points against his Greek opponent to run out a 4-6 6-4 6-4 winner and will meet third seed Diego Schwartzman of Argentina, the world No 19 beating Japan’s Yoshihito Nishioka 6-1 3-6 7-6 (1).
In the women’s draw, Petra Kvitova knocked out reigning champion Angelique Kerber 6-4-6-1 to reach the semi-finals and will now face qualifer Aliaksandra Sasnovich.
Home favourite Ashleigh Barty will play Kiki Bertens in the other semi-final.