Roger Federer and Maria Sharapova topped the lists of seeded players at the Australian Open, with organizers sticking to the world rankings.

Federer, the defending champion, is aiming for his 10th Grand Slam singles title and has been atop the men’s rankings since February 2004.

Sharapova moved to the top of the women’s seedings list at Melbourne Park after No. 1-ranked Justine Henin-Hardenne withdrew from the tournament due to personal reasons.

Sharapova was seeded No. 1 at a Grand Slam tournament only once before _ at the 2005 U.S. Open.

“I don’t see it as putting any extra pressure on me,” Sharapova said. “Whatever you are seeded you’ve just got to go out and play your matches.”

Defending Australian Open and Wimbledon champion Amelie Mauresmo was seeded second.