The 314th-ranked Indian dispatched Nishioka 7-6 (10-8), 6-3 in one hour and 40 minutes in the second round contest.
US Open champion Marin Cilic says his participation in the Australian Open is in doubt because of a right shoulder injury.
Organisers also launched the newly renovated Margaret Court Arena, which will provide a third covered show court after Rod Laver Arena's centre court and the Hisense Arena.
The reigning Australian Open champion is recovering from a leg injury and will be replaced by Russian World No.43 Denis Istomin.
Nadal said the Australian Open final, which he lost to Switzerland's Stanislas Wawrinka, was "the worst hour and a half" he ever spent on a tennis court.
China's Li Na, who picked up her second Grand Slam title at the Australian Open on Saturday, spoke to CNN about her journey to lifting that trophy.
Former Davis Cup coach Enrico Piperno talks about Stanislas Wawrinka's stunning win over World No. 1 Rafael Nadal in the Australian Open final.
Nadal was clearly hampered by a back injury after the first set, but Wawrinka blocked that out of his mind to win the Australian Open 6-3, 6-2, 3-6, 6-3.
Sania Mirza has no qualms in admitting that she and Horia Tecau were 'outplayed' in the Australian Open mixed doubles final.
Wawrinka was aggressive and clinical from the outset against the World No. 1 Nadal, beating the Spaniard 6-3 6-2 3-6 6-3 on Sunday.
Sampras has tipped Nadal to beat Roger Federer's 17 grand slam titles, saying he has never seen anything like the powerhouse Spaniard.
Sania and Tecau succumbed to a 3-6, 2-6 defeat in their Australian Open mixed doubles final against Canada's Daniel Nestor and Kristina Mladenovic.
The pair of Sania Mirza-Horia Tecau lost the Australian Open Mixed Doubles Final to Daniel Nestor-Kristina Mladenovic 3-6, 2-6.
China's Li Na stormed to her second Grand Slam title on Saturday, battling past brave underdog Dominika Cibulkova 7-6 (7/3), 6-0.
Lukasz Kubot and Robert Lindstedt won the Australian Open men's double title with a 6-3, 6-3 win over Eric Butorac and Raven Klaasen.
Li Na made it third time lucky in the Australian Open final, beating Dominika Cibulkova 7-6 (3), 6-0 to become the oldest woman to clinch the title.
A victory would make Nadal the third man to win all four grand slam titles twice, joining Rod Laver and Roy Emerson.
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