Nadal's hot, but is there a dark horse?

A relentless, yet calm, Rafa Nadal opened his 2011 Aussie Open campaign by taking 11 straight games over Marcos Daniel before the Brazilian retired down 6-0, 5-0 with a knee injury.
That's one down and six to go for the swaggering Spaniard in his bid to be the first man since Rod Laver in 1969 to hold all four majors at the same time.
Nadal says he's not fixated on the quest, but you can bet a fair amount he'll push himself to the ends of the earth to win each and every match in front of him.
“It's not an obsession," said Nadal. “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. I never think about winning four grand slams in a row. It's still very far away."
That's a fact, despite the feeling that Nadal is a better player than he was in 2009 when he miraculously stopped Fernando Verdasco and Roger Federer in back-to-back, spectacular five setters to win the Australian title. It's his great rival Federer who is looked at his closest competition to win the crown, followed up by the in-form No. 3 Novak Djokovic and the man who took him out last year, Andy Murray.
But one other dangerous man lurks on his side of the draw, massive Argentine Juan Martin Del Potro, who bullied Nadal and Federer back to back for the 2009 US Open title.
On Tuesday, Del Potro took the court at a major for the first time since last year's Australian Open, when with a sore right wrist that was soon to go under the knife, he fell to Marin Cilic in a five-set classic in the fourth round.
His entire year went to pot. He was full of anxiety, unsure how severe the injury was and how long it would take him to recover. It took about nine months before he could start hitting again and it wasn't until two weeks ago that the 6-foot-6 giant felt good enough to get back into competition.
He won a match in Sydney and dropped another. Out on Show Court 2 here, he took down Israeli all-courter Dudi Sela 7-6 (13), 6-4, 6-4. It was by no means a great performance, but it was impressive enough. While he was somewhat erratic, his big serve was evident, his hammering forehand drove nails into the court, his backhand was fairly clean and, while he didn't move like lightning, he did hustle.
He prefers not to dwell on the past other than to say that everything was difficult. He cannot afford to think too far ahead yet, preferring to be like Nadal, thinking that at any moment, things can go awry, so it's better just to keep his eyes on the next ball.
“I feel good,” Del Potro said. “It's nice for me be here with these players, this tournament, and of course playing a Grand Slam. Today I play good tennis again. To my future, I will try my best. I don't want to think in the past. I won a Grand Slam, but I'm working to improve my game. I don't know if I can play like two years ago or not, but I will try. I'm trying to improve every day. I'm trying to fight with the top 10 players again.”
The 22-year-old Del Potro says he matured during his long layoff and does not think that he's at his 2009 level yet, but why should he be? No one returns from surgery and immediately locks in. He'll face former Aussie Open finalist Marcos Baghdatis in the second round, where he'll be extended from the backcourt more than he was against Sela. And he may have to go up against the fire-breathing Jurgen Melzer in the third round. If he gets through those two, his task will grow larger, as last year's finalist, the cagey Murray, looms.
For Nadal, time is of the essence. After his short match against Daniel, he went out to practice his serve for a half hour as he was dissatisfied with it. Recall that it was that stroke that keyed his first run to the US Open title last fall and he knows that he'll need the same speed and accuracy to win in Melbourne again. He'll play American qualifier Ryan Sweeting, who has never been on the big stage before, in the second round so the Spaniard will be a substantial favorite. The favorite Nadal will be under assault from all quarters, but as it stands today, he'll remain the man to beat until another elite player like Del Potro finds an ethereal level and knocks him off.
“I don't know where is my best level and how far I am from that,” Nadal said. “So I try my best every day. Sometimes you play well; sometimes you play a little bit worse. I can't say if I am playing at my best or not. I think I am in the right way.”