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.

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

Williams said she felt tightness in both knees ahead of the
match and as the match went on, the problematic joint only "got

"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

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

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."