Top rivalry: MELBOURNE, Australia -- It's not quite Martina vs. Chrissy, say, or even Serena vs. Venus. But the developing rivalry between Serena Williams and Maria Sharapova has the potential to turn into an enduring one. Especially if they keep meeting in big matches. And both players look forward to the next one. "She's one of the best competitors out there," Sharapova said Thursday after her 2-6, 7-5, 8-6 loss to Williams in the semifinals. "She's been in those situations when she was down in the third set, and out of nowhere she knows how to turn it around. That comes from experience; that comes from her fighting spirit." Williams, 23, saved three match points and twice broke Sharapova when the 17-year-old Russian served for the match. Williams, who has six career singles Grand Slam titles to Sharapova's one, won their first meeting, at Miami in 2004. But she lost to Sharapova twice later in the season: the Wimbledon final and the season-ending tour championships final. "I definitely think she has a fighting spirit," Williams said, "and I think that's gotten her to where she is today."