The fourth semifinalist is Petra Kvitova, who is coming off a tournament title last Saturday in Tokyo. Kvitova, seeded ninth, earned a berth in the semis with a 4-6, 6-2, 6-4 decision over No 4-seed and local favorite Li Na. Kvitova piled up six breaks over the last two sets.
Williams, ranked No. 1 in women's tennis, was a 6-1, 6-4 winner over sixth-seeded Caroline Wozniacki. Williams won more than two-thirds of the points on serve, losing a total of 154 points over nine games.
She did have her serve broken once but she also took half of the points off Wozniacki's serve and ended up with four breaks.
Radwanska, seeded No. 3, built a big early lead and then hung on for a 7-6 (9-7), 6-4 win over seventh-seeded Angelique Kerber. Radwanska was up 5-1 in the first set before Kerber's comeback. Radwanska was then able to get two second-set breaks for the win.
Jankovic, the No. 8 seed just got by Lucie Safarova 6-7 (3-7), 6-4, 6-4 but needed three third-set breaks to do so.
Williams won the first China Open in 2004 while Jankovic took the title in 2008 and Radwanska won in 2011.
Kvitova takes a 2-0 career mark against Jankovic into the first semifinal Saturday. Williams is 6-0 all-time versus Radwanska. She's won both their meetings in 2013, which were also semifinals.