USA's Serena Williams in action against Czech Republic's Petra Kvitova during day eight of the 2012 Wimbledon Championships at the All England Lawn Tennis Club, Wimbledon. PRESS ASSOCIATION Photo. Picture date: Tuesday July 3, 2012. See PA story TENNIS Wimbledon. Photo credit should read: Adam Davy/PA Wire. RESTRICTIONS: Use subject to restrictions. Editorial use only, including for mobile devices / apps and books. Commercial use only with prior approval. Call +44 (0)1158 447447 for further information.

Wimbledon ladies quarter final: Williams beat Kvitora 6-3, 7-5

Serena Williams’ quest for a fifth Wimbledon title continued after she beat defending champion Petra Kvitova in straight sets.

Despite a 6-3, 7-5 victory the American still wants to improve further if she is to win the title.

“I had to step it up today because I was playing the defending champion,” she told the BBC.

“She’s been playing so well on grass, she hadn’t lost since last year. It was tough.

“But I had absolutely nothing to lose. It was really fun. I’m having the time of my life out here, and I’m enjoying every moment.

“It’s exciting. Everyone thinks about lifting the trophy. It’s something I’ve thought about, but my main goal is to keep progressing.

“If I want to win the title, I have to step it up. There are a lot of people vying for it. I’m happy just to be in the tournament.”

The American is in her 21st Grand Slam semi-final and will face either Tamira Paszek or Victoria Azarenka for a place in Saturday’s final.