The sparkling Spaniard was in imperious form to sweep past a Bolivian making his Australian Open debut 6-2, 6-3, 6-0 on Rod Laver Arena in barely two hours.
The Mallorcan, the first man to be world number one in three different decades, is not only seeking to match great rival Federer's Slam mark, but become the first man in the Open era to win all four Majors at least twice.
It is a big ask for the 33-year-old, who has only won the title once before at Melbourne Park, against a tearful Federer in 2009, with four runner-up finishes to his name.
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"For me it is a positive start. What you want is a first round win and in three sets is even better," said Nadal, who clubbed 38 winners and made only 21 unforced errors.
"This court always brings me lots of positive energy."
Nadal, in a pink sleeveless shirt and matching shoes, was in total charge against the world number 73, storming to a 5-0 lead in the opening set before Dellien held serve, then against the odds broke, before the Spaniard served out the set.
Underdog Dellien was broken in the sixth game of the second set but hit back again to break Nadal for the second time in the match before the top seed again rallied to restore control with some sizzling forehands down the line.
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A flagging Dellien gave it his best shot but Nadal quickly raced 3-0 up in the third set as his physicality and power shone through and there was no way back.
"He (Dellien) has a tough first five games but he had chances to win games," said Nadal, who lost in last year's final to Novak Djokovic.
"He's a fighter, he's a great guy."
Nadal next plays either Argentine Federico Delbonis or Portugal's Joao Sousa.
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