Russian tennis star and former World No. 1 Maria Sharapova was beaten by Germany's Andrea Petkovic in the fourth round of Australian Open in Melbourne on Sunday.

30th-seeded Petkovic beat No. 14 seed Sharapova in straight sets with a 6-2 6-3 result in one hour and 19 minutes to advance to the quarterfinal of the 2011 Australian Open.

Sharapova committed 30 unforced errors compared to Petkovic's 9. Petkovic will now face China's Li Na in the quarterfinal.

Sharapova, who has won three Grand Slam singles titles, including 2004 Wimbledon, 2006 U.S. Open and 2008 Australian Open, has not won a Slam title since she had a shoulder surgery late in 2008.

MOSCOW, January 23 (RIA Novosti)