Maria Sharapova reacts after losing apoint against Serena Williams of the U.S. at the Sony Ericsson Open tennistournament in Key Biscayne, Miami March 27, 2007. Williams won by 6-1 6-1.(Xinhua/Reuters Photo)

Photo Gallery>>>WASHINGTON, March 27 (Xinhua) -- Russia's world female number one Maria Sharapova lost to American Serena Williams 6-1, 6-1 in their Australian Open final rematch at the Sony Ericsson Open in Miami on Tuesday.

Williams, who made short work of Sharapova 6-1, 6-2 in the Australian Open final two months ago, won even more easily in the fourth round match on home soil.

No. 9 Anna Chakvetadze of Russia became the first semifinalist by beating No. 15 Li Na of China 4-6, 7-5, 6-2.

Ranked No. 1 in 2002-03, Williams has played only six tournaments in the past 18 months and has slipped to 18th, but she found her gear back this season.

"Every time I do that I win, so I'm a little superstitious," she said after the match. "I'm working toward getting to be the best. It's an uphill battle."

Seeking her fourth Sony Ericsson title, the No. 13 seed will play No. 8 Nicole Vaidisova from the Czech Republic in the quarterfinals.