In the 30th career showdown between extraordinary sisters who long ago aced the test of time, Venus Williams looked her age while Serena Williams once again appeared to be ageless.
Their sixth career meeting at the United States Open was the most lopsided as Serena, seemingly rounding into form in her third Grand Slam tournament after the birth of her daughter last September, overwhelmed the 38-year-old Venus, 6-1, 6-2, over 72 tension-free minutes in the third round on Friday night.
“Obviously, I played much better today than I actually have since I’ve returned to tennis,” Serena said in an on-court interview after a match in which she was most threatened by a rolled right ankle that required taping by the trainer during the first changeover.
Venus went a level or two higher in explaining the rout that was her sister’s 18th career victory over her against 12 defeats.
“I think that’s the best match she’s ever played against me,” Venus said. “I don’t think I did a lot wrong — she just did everything right.”
Serena’s return to Grand Slam tennis began this year at the French Open, where she withdrew with a pectoral injury before a fourth-round match against Maria Sharapova. At Wimbledon, she reached the final by beating only one seeded player and then lost to Angelique Kerber in straight sets. Williams’s hardcourt summer included the worst defeat of her career, a 6-1, 6-0 thumping by Johanna Konta in San Jose, Calif., and another loss to Petra Kvitova in the Cincinnati event.
But in three rounds at the United States Open, she has lost 11 games. She has been a ground-stroking terror in a tulle tutu, while sending a strong message to the women’s field that she is gunning for a 24th Grand Slam singles title, which would pull her even with Margaret Court, whose total includes tournaments won before the Open era.
Venus had won their last encounter in straight sets at Indian Wells in March, early in Serena’s comeback, but she has not beaten her sister in a Grand Slam tournament since the 2008 Wimbledon final.
Weeks from her 37th birthday, Serena was relentless in attacking Venus’s serve, her most feared weapon across her career. First serve or second, Serena was on it. Venus won only 19 of her 40 first-service points and 9 of 20 on her second. Venus fought off two break points in the second game of the match, was broken in the fourth game and again in a five-deuce sixth game before Serena served out the 31-minute first set at love with an ace.
Be it as the vast underdog or the graceful sentimental favorite, Venus had the Arthur Ashe Stadium crowd pleading for her to do something, anything, to make it a match, to no avail. She netted a forehand for a first-game break in the second set, and the air of inevitability was as oppressive as the humidity that choked the Open during the week.
Not even the sighting and cheering of Colin Kaepernick, the quarterback at the heart of the N.F.L. anthem controversy, could change the dynamic and the dominance. Serena refused to be distracted, staying “really focused on the court,” not interested in sharing her spotlight.
“She played untouchable tennis,” Venus said.
The match was a long way from the 6-2, 6-4 beating Venus gave Serena in their first Open showdown in 2001, a Saturday night final witnessed by luminaries including Spike Lee, Robert Redford, Joe Torre and Mary Tyler Moore.
The showtime sisters once criticized for spotty attendance records at tour events had somehow made it into an ensuing decade and their late 30s, after all. Their primary opponents from those turn-of-the-century days — Lindsay Davenport, Martina Hingis and even some who came later — have long since moved on to various ports of call.
Venus persevered while battling Sjogren’s syndrome, an energy-sapping autoimmune disease. Serena pushed through various mishaps and a harrowing delivery of her daughter last September that kept her bedridden for weeks.
The sisters’ Grand Slam title tally grew lopsided for Serena — 23-7 — but their combined number of appearances in major draws, 149, is a staggering sum, a tribute to staying power.
“Obviously they have been holding the torch for a long time,” said Kathy Rinaldi, the women’s national coach for the United States Tennis Association and the Fed Cup captain. “Venus and Serena have been incredible advocates for our sport — they inspire so many.
She might have been referring to the batch of African-American women who followed — the defending Open champion Sloane Stephens, for one — to the girls who “were crying just to have the opportunity to meet them” when Venus and Serena played for Rinaldi’s Fed Cup team against the Netherlands last February in Asheville, N.C.
Playing against each other, Venus and Serena have seldom seemed to enjoy the occasions, and Friday night was no different.
“Win or lose, it just feels good that that’s done,” Serena said.
As always, there was no celebrating at the finish, no fist-pumping, just gracious smiles and one sister, as usual, moving on.
As to how her sister might fare going forward, Venus said that no one, not even Serena, was untouchable every night.
“It’s not like people don’t try,” she said. “She’ll have to keep that level up.”
An earlier version of this article misstated the number of games Serena Williams has lost through three rounds at the U.S. Open. It is 11, not eight. An earlier version also referred incorrectly to her path to the Wimbledon final. She defeated one seeded player, not none.