Siblings Forever, Rivals for Not Much Longer

"Time!" the chair umpire kept saying Monday, the customary reminder to resume play after a changeover.

But the word had particular resonance given that the Williams sisters were the ones exchanging blows on Centre Court.

Serena Williams, the 6-4, 6-3 winner in this rather anticlimactic fourth-round match, was certainly thinking plenty about it. (Full match report)

"It definitely doesn't get easier," she said of facing her sibling. "But today I was out there, and I thought, 'Wow. I'm 33, and she just turned 35.' I don't know how many more moments like this we'll have." (Also read: How Venus is inspiring Serena's history bid)

It had been a reaffirming 24 hours for enduring American female athletes, with Carli Lloyd, 32, leading the U.S. women's soccer team to the World Cup title and Abby Wambach, 35, playing a role off the bench.

Serena Williams said she planned on playing for years but acknowledged that it was never certain that she and Venus would have the chance to play again on the Centre Court, where they each have won five Wimbledon singles titles.

"I just wanted to take the moment in," Serena said. "I remember when we were 8 years old. We dreamed of these moments. It was kind of surreal there."

Surreal perhaps but, in the end, unsurprising. Venus Williams was the role model and the ringleader when the sisters were very young: the one Serena copied, the one Serena used for a measuring stick.

Venus was the first to turn professional, the first to create a buzz in the small world of professional tennis and the wider world beyond, and also the first to win Wimbledon and reach No. 1.

But Serena has passed her by in terms of career achievements: racking up 20 Grand Slam singles titles to her sister's seven, piling up the weeks at No. 1 and the head-to-head edges over her would-be rivals.

erena set the tone and pace early Monday, striking the ball with tremendous force and winning the first eight points. Venus pulled herself together to make it a contest, but Serena's serve was again the more potent and consistent weapon. She hit 10 aces and won 78 percent of the points when she put her first serve into play, compared with Venus' two aces and 59 percent.

But the statistic that really showed the big sister's vulnerability involved the second serve. Attacking it is a Williams specialty, and each can rob the other of time to  get organized like few other opponents. But Serena won this battle within the battle decisively, converting on 63 percent of her own second-serve points and also winning 67 percent on her sister's second serve, often returning from two big steps inside the baseline.

"Venus did not serve that great," acknowledged David Witt, her hitting partner and coach. "And Serena stepping up to the second serve, it was like the ball was on a tee."

Witt also was disappointed that Venus hit so often to Serena's backhand. "Eighty-five percent of the time," he said. "Serena served great, but you've got to play the percentages. Her strength is her backhand. Everybody knows that."

Serena closed out the first set on serve, hitting three aces in the game. She closed out the match by breaking her sister's serve at love after Venus had lost her previous service game on a double fault.

There would be no handshake afterward, just a long embrace and a chat.

"Sisterly words," Venus said. Asked if she would be back next year, Venus answered, "I think so."

For now, Serena, is back in another Wimbledon quarterfinal. She will face Victoria Azarenka, the former No. 1, on Centre Court on Tuesday.

Azarenka defeated Belinda Bencic, 18, from Switzerland, 6-2, 6-3 in her fourth-round match. Azarenka, seeded No. 23 at Wimbledon, has twice come close to defeating Serena in the past two months, failing to convert on three match points and losing in the round of 16 in Madrid and losing a 6-3, 4-2 lead to Serena in the third round of the French Open.

Overall, Serena leads Azarenka, 16-3, and has never lost to her in a Grand Slam event despite Azarenka pushing her to three sets in the 2012 and 2013 U.S. Open finals.

"Close is not good enough," Azarenka said. "I need to go out there and prove myself. To talk about it is pointless for me. I need to go and do my work on the court and then maybe we can talk after."

The other quarterfinal in the top half of the draw Tuesday will match Maria Sharapova against unseeded American CoCo Vandeweghe. In the bottom half, Garbine Muguruza of Spain will face Timea Bacsinszky of Switzerland, and Madison Keys of the United States will face Agnieszka Radwanska of Poland.

© 2015 New York Times News Service