– Get ready for the latest Grand Slam installment of Williams vs. Williams. One big difference this time: The superstar siblings will be meeting in the third round at the U.S. Open, their earliest showdown at a major tournament in 20 years.

Serena Williams set up the highly anticipated matchup at Flushing Meadows by hitting 13 aces and overwhelming 101st-ranked Carina Witthoeft of Germany 6-2, 6-2 in a little more than an hour in Arthur Ashe Stadium on Wednesday night. Hours earlier, across the way at Louis Armstrong Stadium, Venus Williams did her part with another straight-set victory, eliminating 40th-ranked Camila Giorgi of Italy 6-4, 7-5.

They will play Friday, and it is going to be their 30th tour encounter — plus, of course, all those times when they traded shots from across the net as kids in California, then on practice courts all around the world. It's also soonest the sisters have played each other at any Grand Slam since their very first tour match, all the way back at the 1998 Australian Open. Venus won that one. But since then, it's been Serena who's dominated.

The reason this match comes so early is that their rankings are lower than in the past. Serena is No. 26, playing in only the seventh tournament since she was off the tour for more than a year while having a baby. Even though the U.S. Tennis Association bumped her seeding up to reflect past success, it still placed her at No. 17. Venus is No. 16.

"It's so young in the tournament," Serena said. "We would have rather met later."

She leads the series 17-12, including 10-5 at majors.

Both have been ranked No. 1 and won a combined 30 Grand Slam singles titles, 23 by Serena. They own eight U.S. Open singles crowns, six by Serena.

They've played each other in the finals of all four Slams, including at the U.S. Open in 2001 (when Venus won) and 2002 (when Serena did).

"It's incredible what they've done. I mean, amazing really. Obviously there's been other siblings that have had fantastic careers in tennis, but none anywhere close to what they've managed to achieve," said three-time major champion Andy Murray, whose first major since hip surgery ended with a four-set loss to No. 31 Fernando Verdasco.

Seeded women who advanced on another day with the temperature topping 95 degrees included No. 7 Elina Svitolina, No. 8 Karolina Pliskova, No. 15 Elise Mertens, No. 19 Anastasija Sevastova and No. 23 Barbora Strycova, all in straight sets. Past men's champions Juan Martin del Potro, who beat Dennis Kudla of the U.S., and Stan Wawrinka won, as did 2017 runner-up Kevin Anderson, and No. 11 seed John Isner.

In night matches, Rafael Nadal won 46 of 55 first-serve points and wore down Vasek Pospisil 6-3, 6-4, 6-2 while Jack Sock's rough year continued with a second-round loss, beaten 4-6, 6-3, 6-2, 7-6 (3) by Nikoloz Basilashvili. Twelfth seeded and two-time major champion Garbine Muguruza was upset by Karolina Muchova 3-6, 6-4, 6-4.

Wardrobe malfunction

The U.S. Tennis Association acknowledged that a chair umpire incorrectly warned Alize Cornet for changing her shirt on court at the U.S. Open — the latest example of ways in which men and women are treated differently in tennis.

Off court during a 10-minute indoor break because of excessive heat during Tuesday's first-round match, Cornet changed out of her sweat-soaked outfit.

She rushed to get dressed before play resumed, she said, and put her top on backward, but didn't realize there was a problem until her boyfriend pointed it out. That's when, standing behind a baseline, Cornet pulled off her shirt and put it back on the right way.

Chair umpire Christian Rask then admonished Cornet during her 4-6, 6-3, 6-2 loss to Sweden's Johanna Larsson.

"Of course, I was surprised when I just changed theT-shirt really quick, and he gave me the code violation," Cornet said. "I didn't expect it, and I told him it was pretty weird."

The USTA seemed to agree.

"We have clarified the policy to ensure this will not happen moving forward,'' the USTA said in a statement.