WIMBLEDON, England — Nine bustling years ago, after an awkward Wimbledon semifinal, two under-21 sisters met at the Centre Court net and the winner, Venus Williams, put her arm around the loser and said, “Let’s go, Serena. Let’s get out of here.”

Nine years on, their pioneering father still can’t bear to watch, but the rivalry in one of the jaw-dropping story lines of American sports has matured into a more comfortable phase in which two grown women, ages 29 and 27, have accrued the experience to explain its vagaries.
As they soared toward their fourth Wimbledon final together, Venus said, “I don’t necessarily want her to lose, but for sure I want me to win. Maybe that doesn’t make sense. But when I’m playing someone else, for sure I want them to lose. But I don’t even want to see her” — Serena — “disappointed in any way.
”But at the same time I don’t want to see myself disappointed. You know, I need to get my titles too. So I’m still the big sister, but I’m still going to play great tennis. So it’s definitely, completely different“ from other finals.
It’s different from anything, anywhere, and it may have taken some time to navigate such an uncommon situation. But as they arrived together at another final through Serena’s two-hour, 49-minute gut exhibit Thursday over Elena Dementieva by 6-7 (4), 7-5, 8-6, and Venus’ 51-minute art exhibit over Dinara Safina by 6-1, 6-0, they say it gets less weird.
”The more we play, the better it gets,“ Serena said. ”You know, when we play our match on Saturday, it’s for everything. This is what we dreamed of when we were growing up in Compton (Calif.) 20-something years ago. So, you know, this is what we worked for and this is what we want. Look, I wanted her to win today, and she wanted me to win today.“
At times, too, with 17 Grand Slam titles between them, there’s a sense of just how deeply they’ve drawn from each other, and not just on the practice court.
On Thursday, Venus told a story about that furnace-like will that clearly rages inside Serena, the one that helped her surmount the upgraded Dementieva even when the gaskets of her game fell off all over the court.
At the Sydney rehearsal for the Australian Open in 1998, a 16-year-old Serena, ranked No. 96, trailed No. 3 Lindsay Davenport, 6-1, 5-2, in a quarterfinal. ”I was playing after her, yet again,“ Venus said. ”I’ll just never forget. She came back and won that match. It was so intense. I just learned so much from that, her fight. I think that actually had a huge impression on my career, that one incident, actually.“
So they saved the local newspaper article and, for some time afterward, Venus would read it aloud ”with an Australian accent“ and ”over and over again.“ It apparently described the very force that wriggled through Dementieva on Thursday as Serena served 20 aces and exacted an almost visible will on the large points.
”Even if she’s not playing her best,“ Venus said, ”just the fight that she has, you’re facing that. So there’s so much to face when you play her. It’s definitely a lot to get your mind around. So for me, I’ll be focusing on getting past the player and the fight in the final.“
Here they go again, then, two finalists who wanted the other to win in the semifinals even though that could mean a more severe final. Venus brings the form that has the BBC tennis intelligentsia cooing over its searing precision — 16 winners, one unforced error against Safina — the two straight titles, the 20 consecutive match wins, the celestial 34 consecutive sets won. She’ll run up against Serena, who has won 12 consecutive Wimbledon matches against people not surnamed Williams, has won every set in those except the one against Dementieva, and who possesses that unconquerable will.
They say goodnight Friday. They wake on Saturday. They stride out together onto the world’s favorite tennis theater, and pretty soon they separate the opponent from the sister.
”Well, it’s real easy to separate it when you hit a serve at about 127 and it comes back to you as a winner,“ Venus said. ”You soon realize you’re playing against an awesome player, and you’d better get ready on your toes. So that’s exactly where you separate it.“
Nine years on, Centre Court stages an enduring rivalry you’d think they might like to end up even someday.
”Would I like it to end even?“ Serena said. ”Of course not. Then I wouldn’t win. I’m sure she feels the same.“
”Yes, I do like to be ahead, even though she’s my sister,“ Venus said. ”I do. I don’t know where we are now.“
They’re 10-10.