Novak Djokovic celebrates after completing a straight-sets victory over South Korea's Chung Hyeon on day one of the Australian Open ©Getty Images

Novak Djokovic and Serena Williams successfully began the defence of their Australian Open titles today with straight-set victories at the Rod Laver Arena in Melbourne.

Djokovic beat South Korean teenager Chung Hyeon 6-3, 6-2, 6-4 in his first round match, needing less than two hours in the blistering heat.

"It was a nice opening match with real Australian summer conditions," said the Serb, who is bidding for a record sixth Australian Open crown.

"I think serve is something that I take out from today’s match as the best part of my game.

"It got me a lot of free points.

"In days like this, you need to serve well."

Williams comfortably reached the second round of the women’s event after claiming a 6-4, 7-5 win over Italy’s Camila Giorgi in her first competitive match since losing to Giorgi’s compatriot Roberta Vinci in the semi-finals of the US Open last September.

Earlier this month, the American was forced to pull out of her only pre-tournament warm-up, the Hopman Cup, with a knee injury.

But the six-time Australian Open champion made light of her preparation problems to secure victory after an hour and 43 minutes on court.

"I just needed a break," said Williams, who is chasing a 22nd Grand Slam singles title.

"I have been going non-stop since the Olympics in London, and seeing that this is another Olympic year, I wanted to start the year out really fresh and really go at it again as hard as I can."

Serena Williams beat Italy's Camila Giorgi in her first competitive match in four months
Serena Williams beat Italy's Camila Giorgi in her first competitive match in four months ©Getty Images

Joining Djokovic in the second round of the men’s competition is 17-time Grand Slam champion Roger Federer as the Swiss inflicted a 6-2, 6-1, 6-2 demolition on Georgian Nikoloz Basilashvili in one hour and 12 minutes.

Elsewhere, Czech sixth seed Tomáš Berdych thrashed India's Yuki Bhambri 7-5, 6-1, 6-2 and Japanese seventh seed Kei Nishikori defeated Germany’s Philipp Kohlschreiber 6-4, 6-3, 6-3.

French ninth seed Jo-Wilfried Tsonga needed four sets to beat Marcos Baghdatis of Cyprus 6-4, 4-6, 6-4, 6-2, while the shock of the day was caused by American wildcard Noah Rubin, who knocked out 17th seed Benoît Paire.  

The 19-year-old, ranked 328th in the world, earned his first Grand Slam victory with a 7-6 (7-4), 7-6 (8-6), 7-6 (7-5) success against the Frenchman.

Former world number one Caroline Wozniacki, the 16th seed from Denmark, was the biggest casualty in the women’s draw after losing 1-6, 7-6 (7-3), 6-4 against world number 76 Yulia Putintseva of Kazakhstan.

There were no such problems though for women’s fourth seed Agnieszka Radwańska of Poland, who showed no signs of her recent leg injury in overcoming the United States’ Christina McHale 6-2, 6-3.

Russian fifth seed Sharapova needed just one hour and 13 minutes to see off Nao Hibino of Japan 6-1, 6-3, while Czech sixth seed Petra Kvitová won 6-3, 6-1 against Thailand's Luksika Kumkhum, who beat her in the first round in 2014.