Defending champion Caroline Wozniacki suffered a humiliating 3-6 6-0 7-6 defeat in the China Tennis Open quarter-finals as Italian Flavia Pennetta ran rampant in Beijing.
The world number one's game collapsed in the second set and she was repeatedly left stranded by Pennetta's repertoire of lobs, volleys and powerful baseline returns.
Facing match point, Wozniacki staged a dramatic comeback to force a tie break in the third set but Pennetta superbly lobbed the flat-footed Dane to seal the match.
Former women's world number one Ana Ivanovic became the latest high-profile player to exit the tournament when the Serbian retired from her quarter-final against Agnieszka Radwanska with back problems.
The 23-year-old was a set down when the injury she sustained last week in Tokyo flared up.
Romanian Monica Niculescu came from behind to beat Maria Kirilenko 3-6 6-3 6-4 to clinch a semi-final berth.
Men's top seed Jo-Wilfried Tsonga powered past Spain's Juan Carlos Ferrero 6-3 6-4 to set up a semi-final clash with third seed Czech Tomas Berdych.
Croatian Marin Cilic beat South African Kevin Anderson 7-6 4-6 6-1 and will face Serbian Ivan Ljubicic who reached the last four with a 7-6 6-7 6-2 win over Mikhail Youzhny.
Berdych thrashed Spaniard Fernando Verdasco 6-1 6-0 to set up the showdown with Tsonga.