Serena battles for rights in the lights

Top seed and defending champion Serena Williams breezed into the Wimbledon fourth round but vowed to keep fighting for equal rights under the bright lights of the All-England Club.

World No 1 she may be, but the 31-year-old American was slated as the last match on Court One on Saturday.

With two marathon men's matches before her, she saw her third-round clash with 42-year-old Kimiko Date-Krumm suddenly shifted to Centre Court under the roof and the lights.

Her match did not start until about 7:30 pm, much to her annoyance.

"Well, it's their policy. I've talked about that time and time again, how I'm always fighting for the ladies," said Williams.

"Maybe one day we'll get two matches and the men will get one match, and maybe they'll be able to switch back and forth hopefully.

"But it's definitely something we have to still work on."

Williams was reluctant to get into a slanging match with All-England Club schedulers despite her status as a five-time champion and 16-time Grand Slam singles trophy winner.

"I was a little surprised that I was playing third on after two men. But I wasn't annoyed. I'm able to deal with any circumstance," she said.

Her 6-2, 6-0 win over Date-Krumm gave her a Monday match-up with German 23rd seed Sabine Lisicki for a place in the quarterfinals.

Saturday's win was the 600th of Williams's career as the American continued her gentle cruise towards a sixth Wimbledon title.

A win on Monday will also give her a 35th successive victory, taking her level with sister Venus' record set in 2000.

"Wow, 600 wins. I had no idea. What better place than under the roof at Centre Court to achieve it," said the American.

Williams admitted that despite the late shifting of her court on Saturday, she was a definite convert to playing under the Wimbledon roof for the first time.

"It's definitely special. I prefer this one because it's indoor and it's grass," she said.

"I missed all those indoor carpet tournaments in the '90s that I should have played, and I didn't know that that was really good for my game.

"So, playing indoor on grass for me is like amazing. I love the atmosphere. I love the sound that the ball makes.

"I feel like it's really just incredible. You hear the sound. I feel like the crowd is louder. It just feels really cool."

Lisicki, a semifinalist in 2011 and a quarterfinalist in 2009 and 2012, when she knocked out Maria Sharapova, said she would not be overawed by the challenge.

She can certainly match the American's raw power - coming into Wimbledon, the German had fired 185 aces in 2013, second only to her opponent's 268.