When the U.S. Open decided to move its women’s final to Saturday evening in 2001, it had two very good reasons: Venus and Serena. The Williams sisters didn’t disappoint, as they delivered the tournament one of the best evenings, at least in terms of ratings, in its history — 23 million viewers (the match wasn’t particularly appealing, but I digress). Not even the college football game on ABC — perhaps you’ve heard of the Notre Dame Fighting Irish and the Nebraska Cornhuskers — could outdraw the two girls from Compton, Calif., who didn’t bother playing junior tournaments on their way to the professional tour.

Back then, most tennis fans worried that they would grow tired of all-Williams finals, every second Saturday at the U.S. Open for the next seven years or so. They worried that the sisters, being sisters, might never produce a compelling match.

As it turns out, these weren’t worthwhile concerns. Much to everyone’s surprise, 2001 remains the high point of the Saturday evening final. The sisters squared off again the next year, and this time Serena won convincingly (she lost only 29 games the entire tournament). After that, as far as Flushing is concerned, the sisters fell off the map. Neither played the U.S. Open in 2003, and Venus missed last year’s tournament, too. Neither has reached the final since 2002.

The sisters have this uncanny ability to turn their tennis on whenever they like, no matter how little they have practiced or how few matches they have played in the preceding days or months. No one picked Serena to win this year’s Australian Open, not even her own mother. After two rounds at Wimbledon this year, Venus looked as bad as she had looked in a long while — she nearly lost to Akiko Morigami, a woman half her size and with no serve to speak of, on grass no less. In an instant, the sisters reverted to championship form and all was forgotten.

Yet Venus and Serena have produced no remarkable recoveries at the U.S. Open, their home event and Serena’s self-proclaimed favorite major. In fact, Flushing is the home of some of their worst performances. In 2004, Serena lost to Jennifer Capriati in a match that seemed to turn on a controversial overrule, but essentially was lost by Williams’s lack of fitness. Last year, she beat Amélie Mauresmo at love in the second set and meekly dropped the third set, 6–2.

Venus has disappointed, too. After defeating her sister in 2005, she lost in the quarterfinals to eventual champion Kim Clijsters, then known for her many collapses on the biggest stages, 6–1 in the third set.

Is this the year for a Williams reprise? Can either of the sisters, or both, shrug off lackluster summers and land in the U.S. Open final?

The prospects are not good. Yes, both sisters have won major titles this year, despite playing few tournaments (combined, they have played 71 matches this year, seven less than tour leader Jelena Jankovic). Both have seemed more interested in tennis, at least marginally so, than their myriad other business ventures. Both of them have moved far enough up the rankings to afford them less strenuous draws. These are all positive signs.

Unfortunately, their seeds are such that they may very well land in the same half of the draw (Serena is seeded no. 8 and Venus no. 12). Worse still, Serena, who hasn’t played a match since Wimbledon, is still complaining about her sprained left thumb. At Wimbledon it caused her to hit a lot of one-handed slice backhands, and she didn’t look pretty doing it. She cited it again this week when she withdrew from the Pilot Pen tournament in New Haven, Conn. Her father, Richard Williams, said he wants Serena to sit out the U.S. Open so she can heal (note to the wise: he said the same thing at Wimbledon, where Serena reached the quarterfinals). Venus, meanwhile, withdrew from last week’s Rogers Cup with tendonitis in her right knee.

Considering the state of American tennis these days, an all-Williams U.S. Open final would do a lot of good, much as it did in 2001. We’ve waited five years, perhaps five years longer than any of us thought we would. It’s been long enough.

Mr. Perrotta is a senior editor at Tennis magazine. He can be reached at tperrotta@nysun.com.