The Spaniard 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 world number one Djokovic at Melbourne Park on Thursday.
Murray, who is not ranked 230th in the world, used his protected ranking to enter the tournament as he continues his comeback following a serious hip injury that forced him to undergo surgery and miss most of last season.
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. Dan Evans could also yet make the main draw after beating Jurij Rodionov 6-4, 3-6, 7-5 to reach the final round of qualifying, but James Ward saw his hopes ended in a 6-4, 3-6, 6-3 defeat by Argentina's Marco Trungelliti.
Defending champion Roger Federer takes on Denis Istomin in round one and is in the same half of the draw as Rafael Nadal, who has drawn Australian James Duckworth.
Djokovic, who like Federer is bidding for a record seventh title in Melbourne, will play a qualifier in round one.
In the women’s draw, Johanna Konta will face Australian Ajla Tomljanovic in the first round as the British No 1 looks to bounce back from a disappointing 2018, which saw her fail to progress past the second round at any of the four Grand Slams and fall outside the top 32 in the world, resulting in Konta being unseeded in Melbourne.
Should Konta progress beyond the second round, a number of large obstacles await her after being drawn in the same half as world No 1 Simona Halep and both Serena and Venus Williams. Halep opens her account against Kaia Kenepi of Estonia, who beat her at last year’s US Open, while Serena Williams plays Germany’s Tatjana Maria and Venus Williams takes on Mihaela Buzarnescu of Romania, with defending Australian Open champion Caroline Wozniacki drawn against Belgium’s Alison Van Uytvanck.
Katie Boulter will play Russia’s world No 49 Ekaterina Makarova in what is her first Grand Slam tournament outside of Wimbledon, having broken into the top 100 for the first time towards the tail end of last year. Heather Watson, the world No 93, faces a tricky tie against 31st seed Petra Martic, while Harriet Dart could yet make it a British quadruple in the women’s draw after beating Xu Shilin to reach the final round of qualifying, having recovered from an early break of serve to win in straight sets 7-6 (7/4), 6-1.
Dart's only previous appearance in the main draw of a grand slam came as a wild card at Wimbledon last year, where she took a set off Karolina Pliskova. Dart made a fine start to the season by qualifying at the Brisbane International and reaching the second round, taking her to a career-high ranking of 132.