Melbourne: A ruthless Rafael Nadal preserved his creaky knees for tougher tests down the road by routing Dominican journeyman Victor Estrella Burgos 6-1, 6-1, 6-1 to sail into the second round of the Australian Open on Monday.

Among women, Swiss Belinda Bencic sent an early shockwave by toppling last year's finalist Venus Williams 6-3, 7-5 on an opening day of carnage for American tennis.

Playing his first competitive match since pulling out of the ATP Tour Finals with knee trouble in November, the world No. 1 showed no signs of early season rust as he tore through the evening match at Rod Laver Arena in one hour and 34 minutes.

"Happy for the start, of course," Nadal, who lost last year's final in a five-set classic to Roger Federer, told reporters. "It's a positive start with a good result. If I do months without playing an official match, it's always a little bit more difficult.

"But I started with positive feelings. That's the most important thing for me now. Of course, there are things to improve."

The 2009 champion's bid for a second Australian Open title and 17th Grand Slam win will continue with a step up in class against 52nd-ranked Argentine Leonardo Mayer, who gave him a four-set test in the US Open second round on the way to winning the trophy.

Grigor Dimitrov looked every inch the potential Grand Slam champion as he schooled qualifier Dennis Novak 6-3, 6-2, 6-1 to reach the second round.

The Bulgarian third seed, a semi-finalist at Melbourne Park last year, barely got out of first gear as he displayed his considerable range of skills to oust his Austrian opponent in just 98 minutes on Rod Laver Arena.

"I just tried to be compact, focused, really use every opportunity I had and save some energy," Dimitrov said in a courtside interview.

Home hope Nick Kyrgios launched his campaign with a 6-1, 6-2, 6-4 demolition of Brazilian Rogerio Dutra Silva to continue his bright start to the year.

The volatile 17th seed was on his best behaviour, apart from one first-set rant about a heckler in the crowd, letting his racket do the talking as he treated his fans in the Hisense Arena to an impressive opening salvo.

Kyrgios, one of nine Australian men to start in the main draw, is shouldering his nation's hopes of a first home men's champion since 1976 and could not have asked for a better start.

Britain's Kyle Edmund outfought Kevin Anderson in a court three marathon to send the 11th seed tumbling out 6-7 (4), 6-3, 3-6, 6-3, 6-4 in the first round.

With defending champion and new mum Serena absent, 20-year-old Bencic's brilliant 6-3, 7-5 win under the Rod Laver Arena roof ensured there would not be a Williams sister in the second round of the tournament for the first time in over 20 years.

US Open champion Sloane Stephens tumbled in three sets against China's plucky Zhang Shuai, before 10th seed Coco Vandeweghe was sent packing in two by Hungary's Timea Babos. Shuai won 2-6, 7-6 (2), 6-2.

Jelena Ostapenko, who blazed to the French Open title last June to become Latvia's first Grand Slam champion looked every inch a title contender in a 6-1, 6-4 defeat of Italian veteran Francesca Schiavone to open proceedings on Rod Laver Arena.

For former world No. 7 Bencic, victory was another step on an impressive comeback trail from a wrist surgery that saw her tumble out of the top 300 last year before her return in September.

"I think (before) I had a little bit too much respect, played a little bit careful and safe," Bencic, who was a toddler when Venus won her first grand slam at Wimbledon in 2000, said.

"This time, I really tried to come out and, you know, hit it big. Also tactically be smart on the court."

Venus battled to keep touch in an enthralling second set but the clean hitting and younger legs of Bencic carried away the match in the 12th game.

Crestfallen, Venus's post-match news conference wrapped up quickly, with short responses and a sombre monotone.

"I don't think I played a bad match," she said."She just played above and beyond. I just have to give her credit for that."

Among Indians, Yuki Bhambri struggled to rein in his unforced errors and played well only in patches as his third Australian Open appearance ended with a straight-set first-round defeat at the hands of a seasoned Marcos Baghdatis.

The 25-year-old Indian qualifier, ranked 122, had his chances against world No. 103 Cypriot, but unforced errors cost him the match 6-7(4), 4-6, 3-6 after two hours and nine minutes on court number eight.

Bhambri is yet to win a round in the main draw of a Grand Slam and the Australian Open is the only Major he has played. Agencies