World number one and top seed Karolina Pliskova has been knocked out of the US Open in the quarter finals.

The Czech has been beaten in straight sets 7-6, 6-3 by American Coco Vandeweghe.

Vandeweghe always believed she could transfer her success in the juniors to the senior ranks.

Vandeweghe joins fellow American's Venus Williams and Sloane Stephens in the last four with Maddison Keys attempting to make it an all American semi final lineup this afternoon when she plays Estonia's Kaia Kanepi.