Serbia's Novak Djokovic stretches for a shot during his first round match against South Korea's Hyeon Chung at the Australian Open tennis tournament at Melbourne Park, Australia, January 18, 2016. [Photo/Agencies]

MELBOURNE - Novak Djokovic and Serena Williams started their Australian Open title defense in flawless fashion, securing straight sets wins on the opening day.

Taking center stage on Rod Laver Arena (RLA), the world's two best players and the two pre-tournament favorites, shined in typical Melbourne heat.

Confronted by one of the ATP tour's biggest up-and-comers, South Korea's Hyeon Chung, Djokovic barely broke out of first gear in his 6-3, 6-2, 6-4 first-round win.

The 10-time Grand Slam-winner, who unquestionably had his best year on tour in 2015, dominated in his first best-of-five sets match of 2016, seemingly breaking Chung's serve at will.

It was a quick kill for Djokovic, finishing off the 52-ranked South Korean in a touch under two hours (115 minutes).

The Serbian showed why rivals such as Rafael Nadal and Australian Bernard Tomic have suggested only injury or a divine intervention can prevent the 28-year-old from capturing his sixth Australian crown.

Djokovic said it was great to be back in Melbourne, where he has snared half of his Grand Slam titles to date.

In his on-court interview on Monday, the Serbian star described 2015 as the "best season" of his career, and put last year's incredible form down to the birth of his first child.

Williams, the only player on earth to have had an equally dominant season, also sent a strong message to those in the women's draw.

Going into her eighth Australian Open, the 34-year-old quickly dispelled concerns that a niggling knee injury might impact her title defense.

Williams moved well around the court in her 6-4, 7-5 victory over Italian Camila Giorgi, who gave the six-time tournament winner a good work out in 35-degree Celsius heat.

Williams, who is aiming to become only the third female tennis player to collect 20 major championships, a feat only accomplished by Margaret Court and Steffi Graf, with another win in Melbourne, said her knee was fine.

"It's great. It was an hour and 43 minutes and I didn't feel it at all," Williams told reporters on Monday.