The 19 match wining streak of the Wimbledon and Olympic tennis champion, Serena Williams, has come to an end after she was knocked out of the Cincinnati Masters quarter finals by Angelique Kerber.
The German 5th seed will face the 4th seed from the Czech Republic, Petra Kvitova, in the semi finals, when Serena's older sister, Venus Williams, makes her first semi final appearance since 2010 against Li Na of China.
Also in Cincinnati, the men's world number two, Novak Djokovic is through to the semis against the Olympic bronze medallist from Argentina, Juan Martin del Potro.
In the other semi final, the Swiss world number one, Roger Federer, faces his compatriot Stanislas Wawrinka.
