SHENZHEN, China, Jan. 5 (Xinhua) -- Two seeded players, Agnieszka Radwanska of Poland and Johanna Konta of Britain, encountered tough battles but had different endings at the quarterfinals of the WTA Shenzhen Open here on Thursday.

The top seed Radwanska was knocked out by last year runner-up Alison Riske of the United States while the third seed Konta booked a ticket to the semifinals after beating Kristyna Pliskova of the Czech Republic.

The other two semifinalist are Camila Giorgi of Italy, who defeated Wang Qiang, the only home singles player in last eight 6-0, 6-2, and Katerina Siniakova of the Czech Republic who breezed over Nina Stojanovic of Serbia 6-3, 6-4.

World No. 3 Radwanska faltered in the match today, losing to the eighth seed 6-2, 3-6, 6-0, and also breaking the tradition of the tournament where all top-seeded players became the eventual champions annually during the past four editions.

"I think she was really playing very solid tennis from the begin to the end. She hit the ball well and served well, and very consistent. So, of course, here is my first tournament (this year) , obviously it is disappointing when you lose but hope that a good lesson for the next tournament," the Pole told the press briefing.

After both players split the first two sets, the American who lost to Radwanska 6-3, 6-2 in the final of last year, kept her best form in the decider, sweeping the Pole six games against nil for her sweet revenge to set a meeting with Giorgi in the semifinals. The other semifinal will put Konta against Siniakova on Friday.

"It was an up-and-down match and I just focused on the next point, and tried to play point by point," said the 39th-ranked Riske on court.

After taking the first set 6-4, the British third-seeded Konta encountered a big challenge from Pliskova in the second set, as the Czech fired seven of her match-total 15 aces to level the match after a breathe-taking 13-11 win in the tie-break.

"I think it's a well-known fact that she has the best service on tour. So I knew going to the match that I was gonna have very tough challenge on her service game. So I really just try to neutralize her service as much as possible and just try to get myself into those games, work very hard and try to get some chances," Konta said after the match.

The world number 10 lost her two previous matches against Pliskova, but the Briton was determined not to let it happen again as she bounced back in the third set to seal the match with a 6-3 win.

In doubles action, Raluca Olaru of Romania and Olga Savchuk of Ukraine easily got a ticket to the final as their rivals, top-seeded Raquel Atawo of the United States and Xu Yifan of China skipped the semifinal due to an abdominal strain on the part of Xu.

"This tournament is over for me, as I have been struggling with an abdominal strain since the first day I came here," said Xu. "I will see how it is going for several days and then set off for Sydney." Enditem