By Alastair Himmer

MELBOURNE (Reuters) - A rampaging Rafa Nadal roared through the first round of the Australian Open Tuesday when Brazil's Marcos Daniel retired with the world number one on a tear at 6-0 5-0.

A shell-shocked Daniel immediately called for the trainer to tape up his left knee -- and get a much-needed breather -- and bravely hobbled on until throwing in the towel at 0-5 barely able to walk.

"It's not an obsession," a smiling Nadal told reporters about his quest to win a fourth successive major.

"You can write what you think. I never read a lot about myself. You have your job, I have my job. I'm not thinking about winning the tournament now."

The 24-year-old added: "I never think about winning four grand slams in a row. It's still very far away."

Nadal will join Don Budge (1938) and Rod Laver (1962 and 1969) as the only men to hold all four major crowns at the same time if he wins his second Australian Open.

Melbourne champion in 2009, Nadal mercilessly forced Daniel to scramble from side to side once it became clear his 32-year-old opponent was struggling with his lateral movement.

So embarrassingly lop-sided had the match become that one wag in the crowd broke the silence by shouting "Hang in there, Rafa!" to the amusement of a packed Rod Laver Arena.


Nadal insisted he needed to improve after sneaking in 30 minutes on the practice court to iron out kinks in his service.

"My serve could be a little bit better," he shrugged. "That's the only point I think I can improve if I really want to play well here.

"I worked on it for half an hour after the match. The rest felt okay. (Daniel) is a really nice guy and I feel really sorry for him.

"But I'm a professional and try my best on every point. That's the best thing to do to show respect for your opponent in that situation. I respect him for trying to play."

Daniel told Reuters after the match he suspected cartilage damage on the inside of his left knee.

"It was a disaster," he said before limping off for an MRI examination. "I felt pain two days ago and didn't practice but I felt it again at the start of the match.

"If you are not 100 percent against the top guys it's impossible. I was a bit embarrassed and I wanted to fight but he was just putting the ball left and right and I had no chance.

"I felt like I was 75-years-old!"

(Editing by John O'Brien)