Agnieszka Radwanska maintained the feel-good factor around Polish tennis as she put in a gutsy performance to defeat Li Na and reach the semi-finals of Wimbledon.

Having seen compatriots Jerzy Janowicz and Lukasz Kubot make the last eight of the men's draw yesterday, the pressure was on Radwanska today and the fourth seed delivered after a lengthy clash on Centre Court which she won 7-6 (7/5) 4-6 6-2.

Radwanska, runner-up last year, saved four set points in the opening set and she also had to contend with thigh problems during the match.

Radwanska, who is bidding to win her first grand slam, admitted afterwards that she was struggling to cope with her injury through the latter stages of today's quarter-final win.

"It's because of too much tennis over the last few days," Radwanska said.

"That's why I was struggling. But it's a good problem. I will keep going and try my best."

Radwanska is looking forward to playing Serena Williams' conqueror Sabine Lisicki in the semi-finals on Thursday.

"I am very to happy go through," said Radwanska, who is the highest-ranked player left in the tournament.

"Sabine and I know each other so it will be a big challenge for me to play her on grass."