The No. 2-seeded Serena and No. 3 Venus are in the same half of the U.S. Open field announced Thursday, meaning they could face each other only in the semifinals of the year's last major tournament.
"It is a shame. They're the people to beat. They rise to the occasion at the big ones, especially Serena," three-time U.S. Open champion John McEnroe said.
"In interest level alone, it's too bad," added McEnroe, part of the announcing team at the tournament.
CBS began carrying the U.S. Open women's final in prime time in 2001, a move widely attributed to the sisters' ascension in the sport. Venus beat Serena that year for the championship, and nearly 23 million viewers tuned in, giving the final the largest TV audience of any program that night, including a football game between Notre Dame and Nebraska.
In July, Serena beat Venus at Wimbledon for her 11th Grand Slam singles title -- four more than Venus owns. Serena also leads 6-2 in major finals and 11-10 overall in professional matches.
"There's definitely a rivalry, especially when we step out on the court," Serena said.
"We never talk about numbers, per se. But when we're on the court, we both have in the back of our minds that we won that many matches against each other," she said. "At least it's in the back of my mind."
There won't be Williams-Williams to decide a title, but there could be Federer-Nadal. No. 1-seeded Roger Federer and No. 3 Rafael Nadal were drawn into opposite halves of the field when the draw was held behind closed doors Wednesday.
They have played in seven major finals as Nos. 1-2, including at each of the other three Grand Slam tournaments, with Nadal leading 5-2. But because Nadal recently fell to third in the rankings, there was a possibility the two men who have dominated tennis in recent years would wind up on the same side of the bracket in New York.
Federer is bidding for a sixth consecutive U.S. Open title, but he wasn't always so comfortable in New York.
"I used to struggle here a little bit," he said Thursday, "just because I had trouble with the wind, trouble with the humidity ... my mind would wander during the tournament."
The potential men's quarterfinals are Federer vs. No. 8 Nikolay Davydenko and Roddick vs. Djokovic in the top half; No. 2 Andy Murray vs. No. 6 Juan Martin del Potro and Nadal vs. No. 7 Jo-Wilfried Tsonga in the bottom half.
Nadal could face Murray in the semifinals for the second straight year at the U.S. Open; Murray upset Nadal in 2008 to reach his first Grand Slam final.
Nadal's first Grand Slam action since his fourth-round loss at the French Open will start with an intriguing opponent: Richard Gasquet, the former top 10 player coming off a 2½-month suspension for testing positive for cocaine.
Federer starts off against American wild-card recipient Devin Britton, an 18-year-old who won the NCAA singles championship for Mississippi in May.
Federer could play two-time major champion Lleyton Hewitt in the third round, U.S. Davis Cup player James Blake in the fourth and French Open runner-up Robin Soderling or U.S. Open Series winner Sam Querrey in the quarterfinals.
The women's quarterfinals could be No. 1 Dinara Safina vs. No. 5 Jelena Jankovic and No. 4 Elena Dementieva vs. No. 6 Svetlana Kuznetsova in the top half; Serena vs. No. 7 Vera Zvonareva and Venus vs. No. 8 Victoria Azarenka in the bottom half.
Venus could wind up facing 2005 U.S. Open champion Kim Clijsters in the fourth round. Clijsters recently came out of retirement and is returning to the tournament for the first time since winning it.