Venus Williams brought Kim Clijsters return from injury to an end with a comprehensive 6-2 6-3 quarter-final win at the Diamond Games in Antwerp.
The American was too strong for the local favourite as her lengthy absence with a wrist injury caught up with her.
Earlier on Friday, top seed Amelie Mauresmo set up a semi-final against Alicia Molik with a hard-fought win over Patty Schnyder.
The Frenchwoman lost the first set but battled back to win 4-6 6-4 6-3.
Fourth seed Molik, who reached the Australian Open quarter-finals in January, earlier beat Czech Klara Koukalova 6-3 6-4.
Russia's Anastasia Myskina claimed the final semi-final place in Friday's late game when she beat Katarina Srebotnik in straight sets.
The second seed was made to work in the first set by her Slovenian opponent but ran out a 7-6 6-2 winner.
In the battle between the former world number ones, Williams needed barely an hour to beat her Belgian opponent and remains on course to win the gem-encrusted racket on offer for winning the event three times in a five-year span.
"I have a major motive," Williams said, with the glittering trophy in the background. "I am fully committed here."
Victory in this tournament in 2004 was Clijsters' last WTA tournament win before a wrist injury forced her to the sidelines.
She unsuccessfully tried to come back twice, but her form and lack of wrist pain this time around shows she has regained much of her strength.
"Today I did not play well," said Clijsters, who had been out since last October.
"But the most important thing to me was to have no trouble at all with my left wrist this week. And it was the case. I did not suffer from it at all.
"I am sure that my game will fall into place in the future. I do not know when I will get back to my best level, but it's not so important. To me, it is essential to feel fit again."