(CNN) -- World number one Caroline Wozniacki crashed out of the China Open on Friday, as she surrendered a one-set lead to lose 3-6 6-0 7-6 (7-2) to Flavia Pennetta in Beijing.
Top seed Wozniacki was up 30-0 in the 12th game of the final set and two points away from a place in the last four, but collapsed to hand Penetta her first career victory over the Dane.
"I had 6-5, 30-0 and should have closed the match out," Wozniacki, 21, told the WTA Tour's official website.
"Flavia played some good points at that time, though, and I made a few wrong decisions. It's unlucky. I knew it was going to be tough out there beforehand."
Italian Pennetta will face 11th seed Agnieszka Radwanska for a place in the final, after the Pole benefited from the second-set retirement of Serbian former world No. 1 Ana Ivanovic in their last-eight match.
Romanian qualifier Monica Niculescu continued her impressive run by defeating 2005 champion Maria Kirilenko 3-6 6-3 6-4.
Both players had eliminated one of this year's grand slam champions in earlier rounds, with Niculescu beating French Open winner Li Na and Kirilenko defeating Sam Stosur -- who holds the U.S. Open crown.
Niculescu, 24, will play either Andrea Petkovic of Germany or Russia's Anastasia Pavlyuchenkova in the semifinal.
In the men's draw, top seed Jo-Wilfried Tsonga will play Czech Tomas Berdych for a place in the final after the Frenchman earned a 6-3 6-4 victory over former world No. 1 Juan Carlos Ferrero.
"That was just amazing," Tsonga, 26, told the ATP Tour's website. "Everything was working. I'm just very happy to go through this round, because it's never easy to play against this guy."
Berdych, seeded third for the event, eliminated Spaniard Fernando Verdasco with a straightforward 6-1 6-0 triumph.
The second semifinal will pit Croat Ivan Ljubicic against compatriot Marin Cilic, after the pair beat Russia's Mikhail Youzhny and Kevin Anderson of South Africa respectively.
Elsewhere, defending champion Rafael Nadal will face American No. 1 Mardy Fish in the last four of the Japan Open.
The 10-time grand slam winner scored a 7-6 (7-6) 6-3 over Colombian Santiago Giraldo to set up a clash with Fish, who battled back from one-set down to seal a 6-7 (7-5) 6-4 6-1 success against Australia's Bernard Tomic.
Second seed Andy Murray continued his winning streak by overcoming Argentina's David Nalbandian.
Briton Murray's 6-4 7-5 defeat of the 2002 Wimbledon finalist was his 19th win in his last 20 matches. David Ferrer will be his opponent in the semifinals after the Spaniard beat Czech Radek Stepanek 6-2 7-6 (7-3).
Meanwhile, world No. 1 Novak Djokovic has announced he will not play in next week's Shanghai Masters tournament due to an abdominal muscle strain.
"I am sorry not to be playing in Shanghai, one of my favorite tournaments, but I have not recovered yet from my injury," said Djokovic, who has dominated the sport this year, losing just three matches on his way to three grand slam victories.
"I did another check this week and the results are not good so I need to continue my rehabilitation."