Williams: I can get better
Serena Williams admits she will have to improve in the second week of Wimbledon if she is to lift her fifth Venus Rosewater dish next Saturday.
Williams wasted little time or energy in seeing off Barbora Zahlavova Strycova and Melinda Czink earlier this week, but the American was below par in her three-set thriller over China's Jie Zheng on Saturday.
The 30-year-old lost the first set and needed to dig deep to see off the 25th seed and move into the last 16, where she will face Sara Errani's tormentor-in-chief Yaroslava Shvedova.
Little was known about Shvedova until Saturday afternoon when she pulled off a golden set - winning 6-0 without dropping a point - against 10th seed Errani.
Much harder opponents than the Kazakh await Williams in the latter stages of the tournament - she is due to face Petra Kvitova and Victoria Azarenka en route to the final - and the 13-time grand slam winner concedes she will have to improve to progress.
"I have to make sure I do better," Williams said.
"Usually I return well but I hit so many errors off my returns against Zheng.
"I was just off against her, although she played unbelievable.
"I still think I can play better."
The first thing on Williams' agenda will be to succeed where Errani failed and win a point in the first set.
"Someone told me that she got a golden set. I asked them what it was. I never knew it existed," the four-time Wimbledon champion said.
"I thought she had won four grand slams in a row and the Olympics. "That's the only golden thing in tennis I know of!"
Shvedova has lost the only meeting between the two players three years ago in straight sets, and this is the first time she has made the fourth round at SW19.
Most of her success has come in the doubles game, but her win over Errani has left Williams wary.
"She's a really good player and she's playing well," added Williams, who will play Shvedova first on Court Two.
"She does everything really well. She's a solid player.
"Hopefully I'll be able to win a point in the first set. That will be my first goal, and then I'll go from there."
Williams' main rival for the Championships, world number one Maria Sharapova, will move in to the quarter-finals on Monday if she beats 15th seed Sabine Lisicki on Court One.
Kvitova, meanwhile, has failed to repeat last year's Wimbledon success at other major tournaments and this week she began her title defence with a nervous win over Akgul Amanmuradova.
The Czech has improved hugely since, however, losing just five games in her encounters against Elena Baltacha and Varvara Lepchenko.
Like Williams, Kvitova reckons she must improve if she is to make Saturday's final, but she admits she is still getting used to players raising their game against her thanks to her status as defending champion.
"That's what I was like when I was ranked 60 in the world," said fourth seed Kvitova.
"I wanted to play the best players in the biggest stadiums in the world. I'd always my best against them.
"I was nervous in the first round but I played well in the last two rounds and I will try to have a better game next round."
Kvitova takes on 2010 French Open Francesca Schiavone first up on Court Three on Monday.
The 32-year-old Italian will be looking to make the second quarter-final appearance of a tournament she clearly rates highly.
"Wimbledon is special. It's not like another tournament," Schiavone said.
"It's an honour to be here every year. There's nothing like it."
Second seed Azarenka takes on Ana Ivanovic on Centre Court while Agnieszka Radwanska faces Italian Camila Giorgi on Court Three.
Kim Clijsters, meanwhile, will be hoping her Wimbledon swansong does not come to an end when she plays German Angelique Kerber.