Djokovic won the first of his seven major titles at the 2008 Australian Open, then won here in three consecutive years from 2011 to 2013. His 25-match winning streak at Melbourne Park ended in a quarterfinal loss last year to Stan Wawrinka, who went on to win the title.
Wawrinka began the defense of a major crown for the first time with a 6-1, 6-4, 6-2 win over No. 100-ranked Marsel Ilhan, taking less than 1 hours to breeze through the first round.
In a breakthrough 2014 season, Wawrinka claimed his first Grand Slam title, reached a career-high ranking of No. 3 and helped Roger Federer win the Davis Cup for Switzerland for the first time.
He warmed up for the season-opening major by successfully defending his title at the Chennai Open.
"It's great, bringing me a lot of memories from last year," Wawrinka said of his return. "It was great to come back here feeling happy, happy with my game."
Top-ranked Djokovic had the next match on center court and appeared to be tired and still recovering from illness after his match, saying he'd had a "rough two weeks health-wise but I'm getting up there."
His mood changed suddenly when a court-side interview turned to reflections of 2014, when he won Wimbledon for the second time, married his long-time partner, Jelena, and the couple had a son, Stefan.
"Well those two events are the two most beautiful events I experienced in my life," he said. "Stefan, he's a blessing we received ... now I have even more motivation."