Some fear that Roger Federer's supremacy in tennis is bad for the sport -- his victories generally ensured, if not providentially ordained -- that it strips every tournament he enters of the element of suspense. Others insist Federer's dominance is a boon, sure to galvanize interest in the game just as Tiger Woods's mastery did in golf.

John McEnroe has no use for such angst. Federer's gift with a racket, he argues, is something to be savored -- something so sublime it transcends debate and demands only to be enjoyed.

"You're watching true genius," says McEnroe, hailed as having reinvented the game himself a few decades ago. "It's amazing how easy it comes to him. And we should appreciate that; we don't want him to get hurt. He keeps this up another two, three, four years, and he's going to be the greatest player that ever lived."

The 24-year-old Federer arrives at the U.S Open, which gets underway tomorrow at New York's National Tennis Center, awash in credentials and good karma. The Swiss is the tournament's defending champion, its top seed by virtue of his No. 1 world ranking (held since February 2004) and fresh off his third consecutive Wimbledon title.

Federer followed his Wimbledon three-peat by taking nearly two months off. Then, after picking up his racket again, he sailed through his only tournament since -- defeating Andy Roddick, whom he walloped in the last two Wimbledon finals, to win the title in Cincinnati. The outcome proved two things: Roddick is no closer to unraveling the wizardry of Federer, whose record against him is 10-1; and Federer barely needs to play or practice to retain his perch atop the game.

That sort of dominance has reduced the 2005 U.S. Open, at least on the men's side, to a single story line: Can anyone beat Federer? Says U.S. Davis Cup captain and commentator Patrick McEnroe, "It's all about Federer and everybody else."

While Federer can clearly afford to take an extended hiatus, Serena Williams has been less successful at the quest. Still, few would count her out of this year's U.S. Open, despite her eighth seed, mindful of the power of her groundstrokes and the force of her will.

Serena and Venus Williams ruled the U.S. Open from 1999 to 2002, splitting four titles between them. Just as pundits starting scribbling that their dominance had passed, Venus roared back at Wimbledon this year to claim her fifth title in a Grand Slam event and her first since 2001. The image of the 25-year-old Venus jumping in euphoria defined the achievement, but she has been leveled by the flu since.

"I feel a little more tired than usual," Williams told reporters during a conference call last week. "It's not perfect circumstances, but I'm definitely going to be out there and hopefully have my letdown after the Open."

Serena was out of shape and short of breath at Wimbledon this year, falling to the unheralded Jill Craybas in the third round. She looked no better this month at Toronto, withdrawing after struggling to a second-round victory over a virtual unknown.

"She was not fit at all," said former pro Tracy Austin, now a TV commentator.

The Williams sisters are hardly the only contenders for the U.S. Open women's title with an injury-related asterisk next to their names. Top-seeded Maria Sharapova is recovering from a strained chest muscle -- the result, doctors say, of a growth spurt that saw her shoot up an inch since March. "My muscles are getting used to my bones," said Sharapova, 18, who towers close to 6 feet 2. "That's why I had back problems at the beginning of the year. It's all from growing."

A sore back sidelined American Lindsay Davenport much of the summer, but she won the final in New Haven yesterday and will reclaim the No. 1 ranking from Sharapova tomorrow.

Opening day will also see players stride onto courts that are royal blue, rather than green. It's part of a marketing initiative designed to help TV viewers see the ball and rev up interest in the game. Tennis may be thriving in other parts of the world, but it is waning in the United States. With no Americans in last year's men's or women's final, ratings for the U.S. Open hit record lows. Given Federer's dominance and injuries on the women's side, the prospects for Americans don't look much better this year.

Still, the efforts of one American -- 35-year-old Andre Agassi -- are sure to command attention.

Agassi has won the tournament twice (1994, 1999) in 19 attempts. And he has defied time to make a 20th attempt through a grueling regimen of training, as much match play as his body can take, and all the cortisone injections his doctors permit to tame a painful sciatic nerve that shoots pain from his hip to his ankle when inflamed.

Such a flare-up had Agassi hobbling through a first-round loss at the French Open in May. He withdrew from Wimbledon and vowed not to play anymore unless he was fully fit. That could mean he lasts one round in New York, or it may mean he slogs valiantly through the fortnight. Either way, Agassi insists, he'll set to work with no delusions or expectations.

"It would be great to win," Agassi said earlier this month. "But I have no interest in putting a nice little bow around my career and handing it over to anybody, you know. I go to the Open with the intention of hopefully bringing some inspiration to those who take a few hours out of their day to come watch me. That's what I look forward to."

FEDERER

"A true genius," says John McEnroe

"I feel a little more tired than usual," said 10th-seeded Venus Williams, above. Meanwhile, sister Serena was recently called "not fit at all."