Top seed Novak Djokovic took the first step along the path that many expect will lead to his fifth Australian Open title with a 6-3, 6-2, 6-4 victory over Slovenian qualifier Aljaz Bedene.
Djokovic, the heavy favourite to win the season opening Grand Slam after a superb second half of 2014, barely raised a sweat in his victory over the 25-year-old Bedene, who received courtside medical treatment early in the third set.
The 27-year-old Serb had little trouble against Bedene, who lost the Chennai final last week to Australian Open champion Stanislas Wawrinka, winning the match in 109 minutes.
He will now face either Russia's Andrey Kuznetsov or Spain's Albert Ramos-Vinolas in the next round.
Serena beats challenging Belgian to reach second round
Serena Williams was dragged into a second set scrap by unheralded Belgian Alison Van Uytvanck but put down the minor threat with some powerful serving to reach the second round of the Australian Open with a 6-0 6-4 win on Tuesday.
Having roared through the first set, Williams was on the back foot as the 106th-ranked 20-year-old went for broke, attacking the world number one's serve and pushing her behind the baseline.
However, Williams held firm and crunched an imperious backhand winner on return to seal the contest as her opponent served to stay in the match.
Williams will play Vera Zvonareva in the second round.
Azarenka continues dominance over Stephens
Victoria Azarenka continued her love affair with the bright blue courts of Melbourne Park on Tuesday as the unseeded two-time former champion cruised to a 6-3, 6-2 first round victory over Sloane Stephens.
Azarenka, 25, showed she will be a dangerous floater in the draw after being unseeded at a Grand Slam for the first time since the 2007 US Open following a run of injuries that restricted her to just nine tournaments last year.
She broke the 21-year-old American three times in the first set to clinch it in 29 minutes, and while Stephens fought off five break points in the second game of the second set, her resistance then faded and the tall Belarusian romped to the win.
It is the third successive year Azarenka has beaten Stephens at Melbourne Park, the only place they have met on the WTA circuit, and she will next play either eighth seed Caroline Wozniacki or American teenager Taylor Townsend.
Wawrinka gets title defence off to flying start
Stanislas Wawrinka's title defence got off to a flying start, the Swiss easing past Turkish battler Marsel Ilhan 6-1, 6-4, 6-2 to reach the second round.
Though struggling to land his first serve, the fourth seed barely broke a sweat on a steamy day at Melbourne Park, blasting 34 winners to wrap up the match in less than one and a half hours at Rod Laver Arena.
Wawrinka raised a gasp from the crowd when he took a tumble on the court stretching for a volley late in the first set, but was untroubled thereafter and sealed the one-sided contest with a cross-court volley.
He will play the winner of Romanian qualifier Marius Copil and Spaniard Pablo Andujar in the next round.
Nishikori through to second round after Almagro thrashing
Kei Nishikori stormed into the second round with a 6-4, 7-6(1), 6-2 demolition of hard-hitting Spaniard Nicolas Almagro.
The fifth seeded Japanese, rated a strong contender to capture his maiden grand slam this year after a breakout 2014, broke Almagro six times and sealed the match with a big serve in just over two hours.
The US Open finalist's victory avenged his loss to the Spaniard in the quarter-finals of his home tournament in Tokyo in 2013.
Nishikori will play the winner of Brazil's Joao Souza and Croatian Ivan Dodig.