updated 6:21 p.m. ET July 2, 2009

WIMBLEDON, England - Richard Williams refuses to watch his daughters Venus and Serena play each other. Says he simply can’t bear to see it, no matter the setting, no matter the stage.

So once again, the patriarch of the greatest sister act in tennis history is heading home to the United States before the Wimbledon final. That’s because the women’s singles championship at the All England Club is Venus Williams vs. Serena Williams for the second year in a row and fourth time overall.

The way the sisters won in Thursday’s semifinals could hardly have been more different.

“Serena nearly gave me a heart attack,” Dad said. “Venus played as if she had some place to go, and she was in a major league hurry to get a great dinner.”

Serena went on Centre Court first and came within a point of losing to Beijing Olympics gold medalist Elena Dementieva before grunting and grinding her way to a 6-7 (4), 7-5, 8-6 victory that lasted 2 hours, 49 minutes — longer than any Wimbledon women’s semifinal or final on record.

“Definitely one of my more dramatic victories,” said Serena, who walloped a tournament-high 20 aces. “I felt like I was down pretty much the whole match.”

Venus followed and dominated the No. 1-ranked woman, Dinara Safina, in an astonishingly easy 6-1, 6-0 win that took merely 51 minutes and equaled the most lopsided semifinal result here over the last 74 years.

“The score just showed my level of play,” the third-seeded Venus said. “I was just dictating on every point.”

In Saturday’s final, Venus will be trying to win her sixth Wimbledon and eighth Grand Slam title. Serena will be trying to win her third Wimbledon and 11th Grand Slam title.

It’s the eighth all-Williams major final (Serena leads 5-2) and their 21st meeting on tour (they’re tied 10-all).

“The more we play, the better it gets. When we play our match on Saturday, it’s for everything. This is what we dreamed of when we were growing up in Compton, 20-something years ago,” Serena said. “This is what we worked for, and this is what we want. Like, I wanted her to win today, and she wanted me to win today.”

Venus has won 20 consecutive matches at Wimbledon; if she makes that 21, she will become the first woman since Steffi Graf in 1991-93 to win the tournament three straight years. On Friday, the day before they face off for the singles title, the sisters will wake up at the house they’re sharing during the tournament and head to the All England Club to play as a pair in the doubles semifinals, an event they won last year.

Video Serena rallies for gutsy win Watch highlights of Serena Williams' hard-fought, three-set victory over Elena Dementieva in the semifinals.

Richard Williams said Serena persuaded him to stick around for that doubles match. But he’ll get on a plane Saturday, making sure to remind the pilots not to tell him who wins singles final. How will he find out which daughter is this year’s Wimbledon champion?

Not from TV. Or the Internet. Or by checking their Twitter feeds.

No, he’ll find out the way he does every time one of his kids claims a Grand Slam championship: He’ll read the sign that his neighbors in Palm Beach Gardens, Fla., always post on the gate of their house — “Congratulations, Venus!” or “Congratulations, Serena!”

“All I know,” Dad said, “is a Williams is going to win.”

Serena nearly didn’t make it. Seeded second, she hadn’t lost a set all tournament, yet found herself trailing the fourth-seeded Dementieva.

The Russian is often pointed to as the best player without a Grand Slam title — if it isn’t her, it’s probably Safina — and the biggest weakness in her game long has been her serve.

She double-faulted eight times, but there were moments when that stroke got her out of trouble, including a second-serve ace at 110 mph. Surprisingly, it was her normally sturdy groundstrokes that let Dementieva down. Of course, Serena had something to do with that.

Dementieva’s match point came at 5-4 in the third set, with Serena serving at 30-40. Dementieva had a backhand passing shot set up and tried to hit the ball cross-court, but Serena hit a backhand volley that clipped the tape and landed in.

“The only regret I have — Maybe I should take a little bit more risk on match point, go down the line,” Dementieva said.

It was one of dozens of spectacular points in a match filled with momentum swings and superb play. With the temperature hitting 90, Dementieva slathered white sunscreen on her face and behind her knees, and put a plastic bag of ice on her neck and armpits at changeovers. Both women took time to catch their breath after lengthy rallies.

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