Kim Clijsters avoided following US Open champion Sam Stosur out of the Brisbane International tennis tournament when she beat Iveta Benesova 6-3 6-2 to advance to the semi-finals.
Benesova had beaten top seed Stosur in the second round and was targeting the Australian Open champion in their quarter-final to achieve a special double of beating grand slam champions on successive days but the the 28-year-old Belgian refused to let that happen.
Estonia's Kaia Kanepi earlier provided the upset of the quarter-finals when she beat second seed and world number 10 Andrea Petkovic 6-1 7-6 to set up a semi-final against Francesca Schiavone.
Third seed Schiavone had earlier ground down former world number one Jelena Jankovic 5-7 7-6 6-3 in a drawn-out quarter-final that lasted almost three hours as both players squandered numerous match point opportunities.
Slovakia's Daniela Hantuchova had a walkover into the semi-finals after Serena Williams withdrew on Wednesday with an ankle injury that she sustained in her second round victory over Serbia's Bojana Jovanovski.
In the men's draw, second seed Gilles Simon started sluggishly but managed to overcome Santiago Giraldo 7-6 6-4 in the quarter-finals.
Simon, who beat American Ryan Sweeting and Australia's James Duckworth in the first two rounds, is building nicely for the Australian Open later this month in Melbourne.