Serena Williams from the U.S. acknowledges the crowd after defeating Lucie Safarova from Czech Republic in her women's singles match during session five of the Hopman Cup mixed team event in Perth yesterday. Williams won the match 6-0, 2-6, 7-5. - REUTERS

PERTH, Australia (Reuters):

Serena Williams sent an ominous warning to world number one Justine Henin yesterday that she intends to regain top spot this year.

The world number seven, who will defend her Australian Open title in Melbourne next month, made a winning start to the new season by beating Czech Lucie Safarova at the Hopman Cup.

Shrugging off jet-lag after a journey that began in Miami and took her via New York and Dubai, the American wore a pink skirt, light brown top and matching bandana and looked fitter than she has in recent years.

Despite arriving in Perth only on Sunday, Williams proved her fitness was good by winning a tight battle with Safarova 6-0, 2-6, 7-5.

"Of course I want to be number one," she told reporters. "Of course I want to win Grand Slams, come on, I wouldn't be out here if I didn't have those thoughts."

When she arrived in Australia 12 months ago, Williams was ranked 94th, having slipped as low as 140 in July of 2006 after a series of injuries.

She was given little chance of winning the Australian Open, but the former world number one stormed through the field to take the title, thrashing Russian Maria Sharapova in the final to win her eighth grand-slam singles trophy.

Belgian Henin, who won this year's French and U.S. Opens, is likely to be favourite to win at Melbourne Park but Williams said she believed she could retain the trophy.

"I love challenges, there's nothing better than a challenge and I'm best when I am faced with one," she said.

"Last year I wasn't even in the top 60 and now I'm in the top 10 and just taking it a day at a time."

Williams spent 57 weeks at the top of the rankings between July 2002 and August 2003.