Former world number one Amelie Mauresmo upset top seed Ana Ivanovic 6-3, 6-2 to advance to the semi-finals of the Brisbane International on Thursday.
Mauresmo, who has slipped down the rankings since she won the Australian Open and Wimbledon titles in 2006, dominated the world number five and sealed victory after 67 minutes when the Serbian hit a backhand approach into the net with the court open.
Ivanovic, who was briefly the world's top ranked player last year, has struggled at the Brisbane tournament and her performances have placed question marks over her Australian Open credentials.
The 21-year-old lost last year's final at Melbourne Park to Maria Sharapova.
Fifth seed Mauresmo will now meet either third-seeded compatriot Marion Bartoli or Italy's Tathiana Garbin, who clash later on Thursday.
Earlier, second seed Victoria Azarenka of Belarus initially struggled against Czech Lucie Safarova, who broke the world number 16 three times to hold a 5-1 lead in the first set.
Azarenka, who received a tongue lashing from coach Antonio Van Grichen at the change of ends, then won the next five games before claiming a tough 7-6 6-4 victory on her sixth match point.
"He's the best coach. He always knows when to say something," Azarenka told reporters. "He just told me to keep going, just keep trying. There was not much more to say."
Azarenka will next play Sara Errani of Italy, who beat Belarus's Olga Govortsova 6-3 6-3.
In the men's draw, third seed Fernando Verdasco of Spain came from a set down and needed almost two hours to beat France's Florent Serra 4-6 6-0 6-3.
The world number 15 will next meet the winner of the quarter-final between Japanese teenager Kei Nishikori and France's Paul-Henri Mathieu.