Nadal, chasing a non-calendar year Grand Slam, overran American qualifier Ryan Sweeting 6-2, 6-1, 6-1 to set up an intriguing third round match with exciting Australian teenager Bernard Tomic.

The Spanish nine-time major winner is satisfied with his form, saying his serve had greatly improved from his opening round encounter with Marcos Daniel.

"I think I played a solid match. A few mistakes with the backhand, that's all," Nadal said. "My serve improved a lot since the first day, so I am happy with that.

"My backhand had a few more mistakes than usual and maybe I will have to play a little bit more aggressively, more inside the court. But in general I am happy."

Nadal stretched his Grand Slam winning streak to 23 matches going back to the French Open last June and taking in his victories at Wimbledon and the US Open.

He is also chasing his second Australian Open title and 10th Grand Slam title overall. At last September's US Open he became the youngest man in the Open Era to achieve a career Grand Slam.

"I am very happy about what I have done. That's given me a lot of calmness," he said. "I have probably less pressure right now after last year's season, winning a lot."

Tomic, 18, will have the home crowd behind him when he takes on Nadal after he eliminated Spanish 31st seed Feliciano Lopez, 7-6 (7/4), 7-6 (7/3), 6-3.

The Australian teenager, who is playing with a wildcard, lines up for the biggest match of his emerging career against Nadal.

"I can't believe that I'm playing him," Tomic said. "What an opportunity it is to play him, in a third round as well.

"It's a dream come true. Look, I've got nothing to lose."

Nadal said he was also looking forward to facing Tomic in an expected night match on Rod Laver Arena on Saturday.

"I think it is nice to have a young Australian coming on well and having very good talent and a very good future," he said.

"So I'm excited to go on court and to try to play my best tennis. The crowd is always fantastic here."

Frenchman Tsonga needed 2hr 30min to put away the 51st-ranked Seppi, 6-3, 7-6 (7/1), 7-6 (7/5) and is seeking to repeat his 2008 final appearance where he lost to Novak Djokovic.

Last year's finalist Andy Murray was due to face Ukraine's Illya Marchenko later, while French Open finalist and fourth seed Robin Soderling takes on Luxembourg's Gilles Muller.

Other winners included Russian 10th seed Mikhail Youzhny and 15th seed Marin Cilic of Croatia, while Canadian Milos Raonic hit the fastest serve of the tournament so far -- 230 kilometres (143 miles) per hour -- during his upset of French 22nd seed Michael Llodra.