Neither will be playing in Saturday's final.
Elena Dementieva came close, though, getting within a point of beating one half of the Williams sisters, Serena, before losing 6-7 (4), 7-5, 8-6 on Centre Court.
"The only regret I have: Maybe I should take a little bit more risk on match point, should go down the line," said Dementieva, who led 5-4 in the third set but watched Serena return her passing attempt with a backhand volley winner. "I'm disappointed with the shot because I'm very surprised I didn't go down the line."
In the other match, Venus Williams routed top-ranked Dinara Safina 6-1, 6-0, setting up a fourth Wimbledon final between the American sisters. Serena beat her older sibling to win the title at the All England Club in 2002 and '03, but Venus defeated her younger sister in last year's final to win her fifth Venus Rosewater Dish.
Serena nearly missed out on Saturday's Fourth of July party at the All England Club - a day of outdoor barbecues across the United States in celebration of Independence Day - but her serve came through even when her forehand wasn't working at its best.
"You know, I wasn't sure if it's Serena or Andy Roddick on the other side," Dementieva said of Serena's serve, which produced 20 aces in the match. "Even with that I was able to break her a couple of times and I was in the lead in the third set. Like I said, she's a fighter."
The match, pitting 10-time Grand Slam champion Serena against two-time major finalist Dementieva, produced some of the most exciting tennis of this year's tournament, though Serena was far from playing her most scintillating tennis.
"My forehand didn't show up today. I think (she) went to Hawaii," Serena said. "But I've called. ... Hopefully she'll be back."
Venus had a much easier time on Centre Court, winning the first nine points and saving the only break point she faced. Safina, who lost in the Australian Open and French Open finals this year, won only 20 points all match.
"She's just too good on grass," said Safina, who lost to Serena in the Australian Open final. "It's not my favorite surface and it's her favorite surface."
Safina is half of another successful sibling duo in tennis. She and older brother Marat Safin, a two-time Grand Slam champion, are the only brother-sister combination to have been ranked No. 1 in professional tennis.
Venus' win was the most lopsided women's Wimbledon semifinal result since Billie Jean King beat Rosie Casals by the same score in 1969.
"The score just showed my level of play," Venus said. "I was just dictating on every point."
That fact wasn't lost on the 23-year-old Russian.
"I think she gave me a pretty good lesson today," Safina said.
