Defending champion Serena Williams declares fitness for Australian Open

Defending champion Serena Williams has confirmed that she is fit for this month's Australian Open, despite withdrawing from the Hopman Cup last week with a knee injury.

The 21-time Grand Slam champion sparked concern when her left knee inflamed during a training session at the tournament in Perth.

Williams, who failed to seal a career slam last season after missing out on reaching the US Open final, has not played in the last two months.

However, the American sportswoman has insisted that she is ready for the first Grand Slam of the campaign.

"My body is feeling great now, obviously I had a hiccup but right now it is doing much better," Williams told the Herald Sun. "I've had a few days of training so it's looking good.

"We are all out there killing it. I just need to make sure I'm totally relaxed and at ease. It all comes natural after that. I know what I need to do on and off the court to win big tournaments. That is what I like to do."

The Australian Open gets underway on January 18.