Wozniacki roars back to form

Melbourne - World number one Caroline Wozniacki roared back to form on Wednesday with a thumping Australian Open win which kept her in the running for a maiden Grand Slam title.

Wozniacki, 20, shook off a troubled start to the year with a 6-1, 6-0 demolition of America's Vania King, burying 23 winners to reach the third round and join a list of impressive women's winners.

Belgium's Justine Henin won 6-1, 6-3 against Briton Elena Baltacha and Russia's Svetlana Kuznetsova beat Arantxa Rus 6-1, 6-4. On Tuesday, favourite Kim Clijsters humiliated former finalist Dinara Safina 6-0, 6-0.

In the men's draw, American Andy Roddick, 28, downed Igor Kunitsyn of Russia in straight sets and Czech sixth seed Tomas Berdych beat Germany's Philipp Kohlschreiber in four.

Wozniacki has been questioned over her durability as number one, after she reached the top ranking without winning a major and arrived in Melbourne on a two-match losing streak.

The 20-year-old blonde needs to reach the semi-finals to be sure of retaining the top ranking, which she achieved in October after racking up six tournament wins last season.

But Wozniacki said she was on the "right path" and drew on the examples of Roger Federer and Rafael Nadal, whose constant quest for perfection has seen them dominate men's tennis.

"I always believe you can always get better. Even Rafa (Nadal) and Roger, who are fantastic athletes, they even get better all the time. So they impress everyone every time they step on the court," she said.

"So I think I can still improve everything."

Japanese poster-boy Kei Nishikori enjoyed a four-set win over German Florian Mayer and Spain's Tommy Robredo outlasted Mardy Fish of the United States.

Meanwhile Australian veteran Lleyton Hewitt, 29, refused to call time on his career after going down fighting in a five-set epic against David Nalbandian which wrapped up in the early hours of Wednesday.

"You can always improve. The bar's always getting raised by the top guys," Hewitt said. "If I can stay fit and healthy and play a full calendar, then hopefully I can get better as the year goes on."

Defending champion Federer will be looking for his first ever win over France's Gilles Simon later as he targets a fifth Australian Open title -- which would also stop top-ranked Nadal sweeping all four Grand Slams.

The wary Swiss ordered his coaching staff to draw up a new plan to defeat Simon after the Frenchman won both their previous encounters in 2008.