Venus Williams' comeback ended Friday in her second match after a six-month injury layoff, when she lost in straight sets to Amanda Coetzer in the quarterfinals of the Betty Barclay Cup.
Spraying errors throughout the match against the eight-seeded South African, Williams bowed out 6-3, 6-4.
"It's bitter," Williams said.
The American was the defending champion in the $535,000 clay-court tournament and seeded No. 2. Williams had not played since November because of tendinitis in both wrists.
She won in three sets against Irina Spirlea on Thursday, but her lack of match practice showed dramatically against Coetzer, a player Williams had beaten last year on the way to the title.
A double-fault by Williams gave Coetzer the first set and Williams was hardly able to win a point again until late in the second set. Coetzer had not won in four previous encounters with Williams.
"She played well and I didn't play my best tennis, that's the story of the match," Williams said.
Coetzer's semifinal opponent will be three-time Hamburg champion Arantxa Sanchez-Vicario. The fourth-seeded Spaniard ousted Andrea Glass of Germany 6-3, 6-3.
Top-seeded Martina Hingis rallied to beat former doubles partner Anna Kournikova in three sets and set up a semifinal showdown against streaking Anke Huber.
Hingis beat the sixth-seeded Russian 3-6, 6-2, 6-4.
"I didn't play very well and Anna fought very well," Hingis said. "It's encouraging to be able to win a match like this."
Huber also fought from behind to upset third-seeded Conchita Martinez 6-7 (6), 7-6 (4), 6-2 and brought her winning streak on clay this year to 11.
Kournikova dominated in the first set against Hingis with a big forehand and a nearly error-free performance. But she was unable to maintain the high level and allowed the Swiss to come back.
Hingis led 5-1 in the third but Kournikova saved three match points and won the next three games before tumbling to her eighth loss in nine matches against Hingis, who is seeking her third title of the year.
If she wins the dlrs 535,000 tournament, Hingis will recapture the No. 1 ranking she lost to Lindsay Davenport last month.
Huber, a German trying to get back into the Top 10 after a long slump, wasted three set points to drop the opening set, but fought back in an even match that could have gone either way.
Huber needed two hours, 33 minutes to overcome the Spaniard.
"I am a little bit tired, but hopefully I can get it together tomorrow," said Huber, who two weeks ago won her first tournament since 1996.
Quarterfinals Martina Hingis (1), Switzerland, def. Anna Kournikova (6), Russia, 3-6, 6-2, 6-4 Anke Huber (7), Germany, def. Conchita Martinez (3), Spain, 6-7 (6), 7-6 (4), 6-2 Arantxa Sanchez (4), Spain, def. Andrea Glass, Germany, 6-3, 6-3 Amanda Coetzer (8), South Africa, def. Venus Williams (2), United States, 6-3, 6-4Reuse content