DOHA, Qatar - Serena Williams got some good old family revenge Thursday in Doha, beating Elena Dementieva in straight sets to improve to 3-0 in the Maroon Group and secure her spot in the semifinals. 
Highlights: S.Williams vs. Dementieva
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Williams, the No.2 seed, lost her serve in the third game of the first set to give the No.5-seeded Dementieva a 2-1 lead; but she broke back to 2-2 in a marathon seven-deuce game and took six more games in a row from there to build a 62 20 lead. Dementieva broke back and kept the second set on serve until the last game of the match; she double faulted twice en route to a 0-40 hole in that game and Williams pounced to win, 62 64. Interviews: Serena Cruises on Day 3
"It was definitely a match I had to be really focused for, because she's a really good player," Williams said. "She's one of those late bloomers where she tends to get better and better and better as every year goes on in her career. I was probably playing the most fit girl on tour." Thursday Highlights
"Serena was playing too well for me today," Dementieva said. "I think she's in great shape right now. The way she played against Venus last night was unbelievable. I feel I have a very tough group." Features: Meet the Maroon Group
Serena had won her first two round robin matches as well, against Svetlana Kuznetsova on Tuesday and against Venus Williams on Wednesday. As of Thursday, Serena Williams is the only player in her group guaranteed a spot in the semifinals.
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Read about Venus Williams' victory on Thursday
Read about Caroline Wozniacki's marathon match on Thursday
