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              === Sharapova stays perfect at WTA Championships ===
 
 Istanbul,  Turkey  (Sports Network) -  French Open champion Maria Sharapova
 went 3-0 in her round-robin matches this week at the season-ending WTA
 Championships.
 
 The second-seeded former world No. 1 star breezed past ninth-seeded
 replacement Samantha Stosur 6-0, 6-3 indoors at Sinan Erdem Dome. The sturdy
 Aussie Stosur went 0-2 in her round-robin affairs after replacing ill 2011
 Championships titlist Petra Kvitova in the elite eight-player field on
 Wednesday.
 
 The 2004 champion and 2007 WTA Championships runner-up Sharapova reached the
 semifinals and captured this week's four-player White Group, which also
 featured Wimbledon runner-up  Agnieszka Radwanska (2-1)  and French  Open
 runner-up  Sara Errani  (1-2). The fourth-seeded Radwanska joined Sharapova in
 the semis by outlasting the seventh-seeded Errani 6-7 (6-8), 7-5, 6-4 in
 3 1/2 hours on Friday.
 
 Radwanska will now face Serena Williams on Saturday in a rematch the Wimbledon
 final, which was won by the powerful American.
 
 Also on Day 4 in Istanbul, current world No. 1 Victoria Azarenka (1-1) is
 taking on eighth-seeded Li Na (1-1) in the last of the Red Group action. The
 winner will join Sharapova, the third-seeded former No. 1 Williams (3-0) and
 Radwanska in the semifinals.
 
 If Azarenka wins on Friday, she would end the year at No. 1 for the first time
 in her career and become the 11th woman to do so. If she should lose,
 Sharapova would finish the year at No. 1 with a perfect record, including a
 title, this week.
 
 The  Australian  Open champion  Azarenka  was  last year's  WTA  Championships
 runner-up  to  Kvitova.
 
 In addition to Azarenka, Williams and Li, the Red Group also featured fifth-
 seeded German Angelique Kerber, who went 0-3 in her round-robin play.
 
 Saturday's semifinal winners will meet in the lucrative final on Sunday. If
 Sharapova or Williams title this week, one of them would claim $1.75 million
 as an undefeated champion.
 
 The sizzling-hot Williams has  won 46  of her  last 48  matches overall and is
 a perfect 12-0 against top-five players this season.
 
 The  31-year-old star  is the reigning Wimbledon,  U.S. Open  and  Olympic
 champion and captured  WTA Championships  titles  in 2001  and 2009  and is a
 two-time runner-up at this prestigious event.
 
 
 
 10/26 15:36:07 ET