WASHINGTON - The fifth seed Li Na from China beat German Angelique Kerber 6-4, 6-4 in a last 16 match at the Western & Southern Open on Thursday, and automatically moved to the last four because of the retreat of Agnieszka Radwanska.

Li was the defending champion of the tournament, and she would face the winner between Serena Williams and Simona Halep in the semifinals.

A. Radwanska announced the withdrawal after beating Elena Vesnina 6-0, 6-2 because she needed to attend the funeral of her grandfather on Saturday.