Australia's Samantha Stosur booked her semi-finals spot at the WTA Charleston clay court event with a pair of three-set wins on Friday, ruining the prospect of an all-Williams clash.
Stosur, who turned 28 last Friday, ousted world number 87 Venus Williams with a 6-3, 4-6, 6-3 win in the quarter-finals to set up a semi-final showdown against Serena Williams.
Stosur, of the Golf Coast, was leading Galina Voskoboeva 4-2 in the first set Thursday when the match was halted because of rain. First up Friday on center court, No 2 seed Stosur finished off Voskoboeva with a 6-3, 4-6, 6-2 third-round win.
Serena reached the semi-finals on Friday when injury-cursed Sabine Lisicki quit their last-eight clash in floods of tears.
The American fifth seed was 5-1 ahead in the first set when Lisicki -- whose career went into a tailspin in 2010 when an injury left her barely able to walk -- retired after falling and hurting her ankle.
Stosur posted her first career win over Venus after losing four straight -- all in straight sets, including three on clay.
Stosur hammered four aces, won 61% of her first-serve points and saved eight-of-12 break point opportunities.
Seven-time Grand Slam winner Venus, who was playing on a wild card invitation, made five double faults and won just 42 percent of her second-serve points. The 31-year-old Venus is trying to rebuild a ranking dented by a lengthy injury and illness layoff.
Serena won warm applause from the crowd as she tried to console the stricken Lisicki.
"I totally get it," said Williams, who has endured her own battles with injury and illness, when asked if she sympathised with the German.
Serena posted her second career win over Lisicki, following a 6-1, 6-2 rout last year in the semis of the Stanford event.
In the other quarter-final contest, Czech ninth seed Lucie Safarova surprised fourth seeded Vera Zvonareva of Russia 6-3, 6-3 in an 85-minute match.
Zvonareva, a two-time finalist here in 2010 and 2008, also won their only previous match.