MELBOURNE (AFP) - World number one Rafael Nadal threw down the gauntlet with a devastating display of tennis at the Australian Open on Tuesday as he joined Andy Murray and the Williams sisters in the second round. The muscular clay court king is gunning for his first Australian title and showed he means business with a ruthless 6-0, 6-2, 6-2 demolition of hapless Belgian veteran Christophe Rochus. Nadal reeled off eight games in a row before Rochus got on the scoreboard, with the Spaniard turning the screws again to win in just 77 minutes. "I'm just trying to improve and to be humble because every match is different and every match is tough," he said, adding that he was fully recovered from the knee injury that blighted the tail end of 2008. "I'm very happy because I'm over the injury and at one of the greatest tournaments in the world." Also through is Murray, the fourth seed. As temperatures soared past 40 Celsius (104 Fahrenheit) earlier in the day, the Scot barely broke a sweat against Romanian Davis Cup captain Andrei Pavel who retired with a back injury when Murray was leading 6-2, 3-1. The 21-year-old is now undefeated in six matches this season as he goes in search of Britain's first Grand Slam title since 1936. "It's unfortunate I had to stop but I felt like I was hitting the ball well," he said. "I guess if you want to do well in the tournament, it's good to conserve some energy." Second-seeded Serena Williams was equally comfortable in her 6-3, 6-2 mauling of China's Meng Yuan, not needing the ice vests offered to players between games in such sizzling heat. Matching her sister, sixth seed Venus hardly broke stride as she sauntered past Germany's Angelique Kerber 6-3, 6-3. While they cruised, Russian fourth seed Elena Dementieva survived a gruelling test before grinding down Germany's Kristina Barrois in three sets, while Polish ninth seed Agnieszka Radwanska became the biggest casualty so far. Australian hope Lleyton Hewitt joined Radwanska on the scrap heap after slumping in five sets to Chilean 13th seed Fernando Gonzalez.The experienced Serena is looking for her 10th major crown and her fourth in Melbourne. Only a few select women, including Steffi Graf, Martina Navratilova and Chris Evert, have won more major titles than the formidable 27-year-old. Forgoing her usual flashy outfits for a nondescript dark blue number, the American powered past Meng in just 75 minutes. "I think I hit some pretty solid shots, sometimes I even went for some shots just to try something different," she said, downplaying the effect of the heat. "There wasn't so much humidity out there, the dry heat is actually better than the humidity. But it was definitely extreme conditions." Venus, who has yet to lift the Melbourne title, was untroubled by Kerber. "For me, it's about getting to that next round," she said. "I don't know who I'm going to play. I don't know who will win. I don't know who will lose. I've got to get there. That's really what it's all about for me." Dementieva is widely regarded as a dark horse for the championship after already winning two titles this year. But the Beijing Olympic gold medallist was pushed to the limit in the 7-6 (7/4), 2-6, 6-1 win, extending her win streak this year to 11 matches. "I'm just happy to survive," she said. Other players to progress included 2006 champion Amelie Mauresmo, who showed no signs of the thigh strain that forced her out of the Brisbane International. On the men's side, fifth seed Jo-Wilfried Tsonga, the runner-up to Novak Djokovic last year, looked ominous in his straight sets win, as did sixth seed and fellow Frenchman Giles Simon. Ninth seed James Blake overcame Canadian qualifier Frank Dancevic.