China's Li Na ended the fairytale run of Russia's Ekaterina Makarova to reach the semi-finals, beating her 6-4, 6-7, 6-2.
Meanwhile, Belarus' Victoria Azarenka came through a tough challenge from Serbia's Ana Ivanovic to reach the quarterfinals at the US Open tennis tournament.
Serena Williams again was at her dominating best when she beat Spain's Carla Suarez Navarro 6-0, 6-0 to reach the semi-finals.
Li Na and Serena will face-off for a pace in the finals.