Williams retires with left knee injury; Henin, Ivanovic win
MADRID, Spain -- Serena Williams retired with a left knee injury after one set Wednesday and defending champion Justine Henin advanced to the semifinals at the Sony Ericsson Championships.
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Ana Ivanovic moved closer to the final four by knocking out Daniela Hantuchova with a 6-2, 7-6 (9) win in red group play.
Williams was treated by the tournament doctor before the start of the ninth game. She retired after losing the first set 6-4 to seventh-ranked Anna Chakvetadze and went to the hospital to get an MRI on her swollen knee.
Williams had knee surgery in 2003 and also missed 10 events in 2006 because of knee problems.
The fifth-ranked Williams has reached the final in all three previous appearances at the event, which features the top eight players.
Williams said she felt tightness in both knees ahead of the match and as the match went on, the problematic joint only "got worse."
"It's beyond unfortunate this has happened and I can't even stress how disappointed I am," she said in a statement. "It's my intention to play on in this event, I have been training really hard, I came over to Europe ... with the goal in mind of doing really well here."
If Williams is not fit to face Henin on Thursday, Wimbledon finalist Marion Bartoli will replace her for the last two matches of the round-robin tournament.
Henin beat third-ranked Jelena Jankovic 6-2, 6-2 to move into the semis for the third straight time after Williams retired.
Henin broke Jankovic's serve six times to win her 22nd straight match and improve to 9-0 against the third-ranked Serb.
"From the first point to the end, I took all of my chances, all of the opportunities and it was her first match, so maybe I had a little advantage because I could play last night," said Henin, who improved to 11-1 indoors this year.
Henin broke serve in the first game, and Jankovic broke back to level the first set at 2-2. But the top-ranked Belgian came to the net to break twice more to close it out against the first-time qualifier.
She broke Jankovic's serve three more times in second set.
"I couldn't really find my game at all, I couldn't really do anything," Jankovic said. "So many things wrong. I have to somehow stay positive because I'm still in the game. I still have two matches to go."
Facing Chakvetadze for the first time, Williams broke in the second game of the first set. But with two of her four double faults in the third game, the Russian had the first of her three breaks.
The fourth-ranked Ivanovic broke Hantuchova three times to rush out to a 5-0 lead in the first set.
"It was really nerve-racking, but I'm very happy to win another match tonight," Ivanovic said. "After two late nights I can use the day off tomorrow."
Copyright 2007 by The Associated Press