A streaker failed to distract Maria Sharapova and the other top women's seeds also marched through to their allotted places in the Wimbledon semi-finals on Tuesday.
Fourth seed Sharapova, the 2004 champion, beat fellow Russian Elena Dementieva 6-1, 6-4 while top seed Amelie Mauresmo, second seed Kim Clijsters and number three Justine Henin-Hardenne won their quarter-finals.
Clijsters ended China's hopes of a first Grand Slam singles semi-finalist when she overcame Li Na 6-4, 7-5 and will face Belgian compatriot Henin-Hardenne in the last four.
Henin-Hardenne, who beat Clijsters in the semi-finals of both the French Open and the pre-Wimbledon Eastbourne event last month, was a 6-4, 6-4 winner over French qualifier Severine Bremond.
Mauresmo will face Sharapova after surviving a determined challenge from another Russian, Anastasia Myskina. The Australian Open champion came through 6-1, 3-6, 6-3.
Sharapova's head was not for turning on Centre Court. She was 6-1 and 3-0 up when a naked man ran on to the playing area and performed a cartwheel in front of her.
Security eventually bundled him off, and after losing three successive games, Sharapova recovered her composure to finish off Dementieva.
"It was real bizarre," said Sharapova, who is through to her third successive Wimbledon semi-final. "Even more bizarre that it took 10 seconds for security to come out."
Wimbledon's All England Club said later it would review its safety procedures.
Mauresmo was given the toughest ride of all the leading contenders by 2004 French Open champion Myskina.
"I started to make way too many unforced errors. But it's a good lesson to learn and I'm trying to learn after every match," said Mauresmo, who turns 27 on Wednesday.
NERVOUS LI
Despite admitting to being nervous as the first player from China to reach the last eight of a Grand Slam singles event, Li gave US Open champion Clijsters a decent test on Centre Court.
The 24-year-old Li had a set point at 5-3 in the second set before falling away. "I was very nervous," she said. "I think for those kind of level of match everyone is very nervous."
Clijsters, who has never been beyond the semi-finals at Wimbledon, said: "Now I really don't care who's standing in front of me, I have nothing to lose. I'm going to go for it."
Like her Belgian rival, Henin-Hardenne has not dropped a set on her way to the last four and the 2001 runner-up has now won her last 16 matches after downing Bremond.
The French qualifier, who had never been beyond round two at a Grand Slam before Wimbledon, lost her serve in the opening game of each set but still made Henin-Hardenne fight hard for victory.
"She was coming a lot to the net," said three-times French Open champion Henin-Hardenne, who will complete her Grand Slam set if she wins the grasscourt Grand Slam.
"She wasn't scared of playing on court number one in this kind of situation. I had to fight a lot on every point.
"But I was ready for this. It's important you are ready to fight even if on the paper it looks easy."