In Thursday's third round, she beat former world No. 1 and five-time Grand Slam winner Venus Williams of the United States, also in straight sets.
Elsewhere on Friday, fifth-seeded Francesca Schiavone of Italy trounced No. 3 Patty Schnyder of Switzerland, 6-1, 6-1; unseeded Kveta Peschke of the Czech Republic was a 6-4, 6-3 winner over No. 4 Dinara Safina of Russia, and unseeded Alona Bondarenko of Ukraine topped Nathalie Dechy of France, 5-7, 6-4, 6-0.
In Saturday's semifinals, Peschke faces Bondarenko, and Radwanska meets Schiavone.