Serena crashes out as Venus reaches first semi of 2012
Serena Williams tumbled out of the Cincinnati Masters on Friday evening, going down 6-4 6-4 in the quarter-finals to Angelique Kerber.
Williams spurned four opportunities to break the German's serve, but failed on each occasion while Kerber converted on her two break points. Indeed, Kerber required just one break of serve in each set as she matched Williams from the back of the court.
A shaky first serve hampered Williams throughout the match, as she landed just 48% of her first deliveries.
The 30-year-old had won 19 straight matches dating back to the start of Wimbledon this year, but appeared sluggish in Friday's defeat. Kerber, meanwhile, displayed signs of nerves while serving for the match before sealing victory with an ace.
Serena's sister Venus Williams, though, reached her first singles semi-final of 2012 by beating Sam Stosur in an epic battle. Williams, who returned to the tour earlier this year following a break of several months due to illness, triumphed 6-2 6-7(2) 6-4 in two hours, 34 minutes.
She seemed to have blown a golden opportunity when she was broken while serving for the match, but recovered her poise to close out the victory.
She grabbed seven breaks in all to record her sixth win over Stosur from seven attempts. Serena said of Venus: "She's doing really well. She's playing much better than I am, moving better, serving well, moving up to short balls, hitting well - everything she's doing is great.
"I thought I was inspired, but I couldn't transfer it over to my game."
Earlier in the evening, top seed Agnieszka Radwanska was upset by the in-form Li Na. It was a comfortable win for the French Open champion, who claimed a 6-1 6-1 victory in 70 minutes.
Meanwhile, in the third round, Caroline Wozniacki was brushed aside by Anastasia Pavlyuchenkova, who won 6-4 6-4. Petra Kvitova then defeated Pavlyuchenkova to reach the semi-finals in the last match of the evening.