MELBOURNE (Agencies) - World number one Rafael Nadal headed straight to the practice court for more work after his curtailed opening match at the Australian Open on Tuesday. Nadal moved through to the second round after his first opponent Marcos Daniel retired during the second set with a knee injury. The Spanish top seed, bidding for his fourth straight major title to complete a non-calendar year Grand Slam, was leading 6-0, 5-0 when the Brazilian retired with a painful left knee. Nadal was only on court for 47 minutes and the nine-time Grand Slam champion sought more work on his service after the injury-shortened match. I practised for half-an-hour after the match. Hopefully my serve is going to be fine, he said. Nadal was sympathetic with Daniels plight after he was forced out with a knee injury in the quarterfinals to Andy Murray in last years Australian Open. Hes a really nice guy and Im really sorry for him, he said of the 93rd-ranked Daniel. I wish him all the best for the recovery. Hopefully it is nothing really important. Nadal, who extended his Grand Slam winning streak to 22, said he was not concerned about missing an opportunity for match practice. Save energy or not, I think the way that the match ended doesnt make a big difference to me, he said. Daniel took a medical timeout after losing the opening set in 19 minutes and looked a dejected figure as he hobbled around centre court unable to chase down Nadals volleys. After his sixth service break, Daniel walked to the net and conceded defeat to Nadal. I was practising two days ago and I made a bad movement, I felt a very strong pain, Daniel said. I was feeling really bad. Today I knew it was going to be really tough. If you are not 100 percent focused on the match, with this kind of player, it is impossible. Nadal, who is recovering from an illness which struck him during the Qatar Open, said it was difficult to assess his form after the abbreviated match. Its difficult to say if I played really well or played bad, he said. I think I played all right. I played some good shots, some long shots. The serve can be a little bit better. I have to improve more (on serve) if I want to play well here. So thats it. For the rest, forehand and backhand, I felt okay. Nadal is chasing his second Australian title and his 10th Grand Slam trophy in Melbourne. At last years US Open, Nadal became the seventh man in history to win all four Grand Slam titles and became the youngest man in the Open Era to do so. It was plain sailing for most of the other leading mens seeds on Tuesday with Russias Mikhail Youzhny (10), Austrian Jurgen Melzer (11) and Croatias Marin Cilic (15) all advancing to the next round. Another one of those top five that Daniel mentioned was Andy Murray, the 2010 finalist who also advanced when Karol Beck retired with a shoulder injury in the third set of their first-round match. The fifth-seeded Murray, who was leading 6-3, 6-1, 4-2, was the only man to beat Nadal in a Grand Slam tournament last year, the quarterfinals at Melbourne Park. Youd rather finish the match off without your opponent being hurt, Murray said, but it does happen quite a lot. So you just have to move on and get yourself ready for the next round. Fourth-seeded Robin Soderling had to go the distance but was rarely challenged, completing a 6-4, 6-2, 6-2 win over Potito Starace of Italy. Australian wild-card entry Bernard Tomic advanced to the second round with a 6-3, 6-2, 7-6 (5) win over Jeremy Chardy of France. Tomic could meet Nadal in the third round. Another winner was 2009 U.S. Open champion Juan Martin del Potro, who played only three matches last year due to a right wrist injury. He beat Dudi Sela of Israel, 7-6 (13), 6-4, 6-4. I dont want to think in the past, del Potro said. I won a Grand Slam, but Im working to improve my game. I dont know if I can play like two years ago or not, but I will try. On the womens side, U.S. Open champion Kim Clijsters did nothing to dent her growing status as favourite by routing fellow former No. 1 Dinara Safina 6-0, 6-0. The U.S. Open champion never allowed the 2009 Australian Open finalist to get into the match, placing pinpoint forehands to all areas of the court. When Safina did have an opportunity to return, her many unforced errors gave away the point to Clijsters. I expect my opponent to come out and play their best tennis, said Clijsters. She obviously didnt do that today. Safina was less polite. I was sitting in the changeover, and I was like, OK, at least how can I get a chance to hurt her? Safina said. There was nothing that I could do to hurt her. Embarrassing. Elsewhere, No. 15 Marin Cilic of Croatia beat American qualifier Donald Young 6-3, 6-2, 6-1 to advance along with No. 7 David Ferrer, No. 10 Mikhail Youzhny, No. 11 Jurgan Melzer, No. 20 John Isner, No. 31 Feliciano Lopez and No. 32 Guillermo Garcia-Lopez. Former No. 1 Lleyton Hewitt and David Nalbandian of Argentina were scheduled to meet in a later first-round match in a replay of their 2002 Wimbledon final won by the Australian. Hewitt leads the series 3-2 but has not beaten Nalbandian since their controversial 2005 Australian Open quarterfinal in which the pair bumped into each other purposely on a changeover. The video clips of that altercation have featured prominently on television promotions of the night Rod Laver Arena match. After the 2005 match, won in five sets by the Australian, Nalbandian said Hewitt was not a gentleman' and nobody is friends with the Australian. Hewitt said Nalbandian was not the cleanest guy. No. 2-ranked Vera Zvonareva began her bid to reach a third consecutive Grand Slam womens final with a 6-2, 6-1 win over Sybille Bammer. Zvonareva lost to Serena Williams in the Wimbledon final and to Kim Clijsters in the U.S. Open final last year. She dominated the first set against the 30-year-old Bammer, conceded only four points in the first four games of the second set and didnt allow the Austrian to hold until the sixth game. Ana Ivanovic, the 2007 French Open champion and 2008 Australian Open finalist, slumped to her worst result in seven years at Melbourne when she lost 3-6, 6-4, 10-8 to Russias Ekaterina Makarova. The 19th-seeded Ivanovic saved five match points before finally going out. Also advancing were French Open finalist Sam Stosur, the fifth-seeded Australian who beat American wild-card entry Lauren Davis 6-1, 6-1; No. 12 Agnieszka Radwanska, who took six of the last seven games.