By Martin Parry

Defending Australian Open Champion Serena Williams speaks to the press in the lead-up to the Australian Open tennis tournament in Melbourne on January 16, 2010. The Australian Open will be played from 18 - 31 January, 2010. AFP PHOTO/Paul CROCK

MELBOURNE, Jan 16, 2010 (AFP) - Defending champion Serena Williams has played down concerns about her troublesome left knee after cancelling a practice session on Saturday ahead of the Australian Open.

The world number one lost in the semi-finals of the Sydney International on Friday to Elena Dementieva and was inconvenienced by the injury with her knee strapped for the match.
She admitted it troubled her from the start, but said it now felt better.

"The knee is much better. It was good for me to get all those matches in," she insisted.

Asked if the injury had hampered her preparation for the opening Grand Slam of the season, she replied: "Absolutely not. If anything, it helped.

"I played a lot of matches in a row, back to back. I had a long three-set match (in the semis)."That was good preparation for me because I do plan on playing both singles and doubles here." Nevertheless, concern remains after she pulled out of her scheduled practice session Saturday. Williams said she had enough practice with the Sydney warm-up event.

"Well, I definitely had a lot of practice with Sydney, getting that far. I don't want to push it, go too far," she said.

"I definitely want to do the best I can, obviously, but I also want to pace myself. Hopefully I can play seven single rounds and six double rounds."

Williams is searching for her 12th Grand Slam singles title at the Australian Open next week to put herself alongside Billie Jean King as one of the all-time greats.

The four-time winner at Melbourne Park is clear favourite to lift the trophy again after a stellar 2009 but faces a tougher task this time with many top players making significant improvements over the past year.
But Williams -- the winner here in 2003, 2005, 2007, 2009 -- has the motivation, knowing one more victory will draw her level with the legendary Billie Jean King with 12 Grand Slam titles.

She acknowledged that her task had been made harder by the return of Kim Clijsters and Justine Henin, but was excited by the new challenge they posed.

"What an amazing effort and quality for her (Justine) and Kim Clijsters. It's so good to see two such good players back," she said, commenting on the classic Brisbane International final this month that featured the two Belgians.

"It's good to be back and be a part of that strong field. Just being in the draw is awesome."
Williams opens her tournament against Poland's Urszula Radwanska, the younger sister of 10th seed Agnieszka Radwanska.

They have played each other before and Williams is not underestimating the challenge.
"I've played her before at Wimbledon. She's a tough cookie, a tough player. And she's definitely no push over," she said.

"She's a younger sister, and younger sisters always want to play really hard and really tough. I know that for a fact."

If she progresses, Williams faces a possible quarter-final against Belarus seventh seed Victoria Azarenka or Russian ninth seed Vera Zvonareva and is projected to meet sister Venus in the semis.