NEW YORK - Let's get right down to business on Day One of the U.S. Open, shall we? Andy Roddick and Kim Clijsters, two players who have won the U.S. Open but no other major, were featured on Monday's day card at the National Tennis Center.

And while Roddick's condition is more perilous, both players are in a do or die situation, insofar as that ever obtains in a sport where each of the four Grand Slams played annually offers potential for redemption and re-invention — as well as horror and desperation.

But let's face it, Roddick has been knocking at the door of two majors, Wimbledon and the U.S. Open, since he won his lone Grand Slam win here in 2003 — a feat that catapulted the raw-boned, fresh-faced, just-turned-21 kid into a star.

The following year, Roddick lost a tough five-set quarterfinal to Joachim Johansson, but then flamed out in the first round in 2005 to Gilles Muller. That wiped out a lot of Roddick's U.S. Open capital, and he spent years rebuilding it.

Roddick lost back-to-back matches to eventual champion Roger Federer after that loss to Muller (one of them in Roddick's second final on Arthur Ashe stadium), and in 2008 he was laid low by Novak Djokovic — no shame in that. But last year's third-round loss to countryman John Isner had to be a bitter blow salved only slighty by the sense of kinship between the men.

Now Roddick is the No. 9 seed, and the graphic portait of his ranking history is one of those "worth a thousand words" tableaux. Twice in recent years, Roddick has re-energized a slipping game with the help of a coach; first, Jimmy Connors, then most recently Larry Stefanki.

You get the sense that banging the reset button works for a guy like Roddick, who's always been willing to turn over every stone in what is a very demanding quest, given the limitations of his game: keeping himself in the mix near the top. His real hole cards in that regard have been his proficiency at Wimbledon and his history at the U.S. Open.

But Roddick was staggered at Wimbledon this year in the fourth round by Yen-Hsun Lu of Taipei, losing in the most unexpected way — 9-7 in the fifth. So while he doesn't have a great 2009 finish to defend here (nor the cartload of ranking points), an indifferent performance will leave people wondering if he isn't on that inevitable downward slide.

And given the diligence with which Roddick has worked on his game and fitness, you have to wonder where he could go from here. Remember, Connors and Stefanki didn't engineer surges by Roddick simply by force of their persuasive personalities. They did hard, targeted work. But what's there left to work on in Roddick?

As long as Roddick has that big serve, he'll be a potential factor on any medium to fast court, particularly if the bounce is low and the ball goes through quickly. But if he doesn't have a good tournament here, he'll find himself in a position where he has to work harder to achieve less, unless he makes a drastic decision to target a relatively small number of tournaments—rankings be danged.

You might assume that Clijsters is much younger than Roddick, but there's barely a year difference (Roddick is 28, Clijsters 27). And she's been to the final of the last three U.S. Opens in which she's played, and won the last two (she beat Mary Pierce in 2005, and came back from an extended break to win the tournament last year).

When Clijsters won here last year, in just the third tournament of her comeback, it seemed that she might present a consistent challenge to Serena Williams and perhaps even dominate the WTA tour. But while the women's game is more wide-open than ever, Clijsters hasn't been able to capitalize on the chaos.

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Now that Justine Henin has called it quits for 2010, and the day-to-day impact of the Williams sisters seems to be diminishing, the stage is set for Clijsters do do what her fans have been hoping for and expecting since she first joined the tour: emerge as the dominant star.

Clijsters has all the earmarks of an old-school style prolific champion. She's focused on a mangeable combination of her young family and tennis. She has no desire to be a movie star or rock musician. She doesn't run with a fast crowd. She's worked hard, and has also worked through the personal issues that turned her against tennis, a significant victory for a woman who turned pro at 14 and was in the Top 5 by the age of 18.

We sometimes forget that Clijsters played an awful lot of tennis (a decade, to be precise) before she pulled the plug in the spring of 2007, while ranked No. 4 in the world. She'd already been to a dozen semifinals or better at majors, and had appeared in five finals (winning just one, here in New York).

Since her surprising victory here a year ago, the question, "just how good is she?" has been approaching critical mass. Is she the same old Kim, pleasant, fun, happy-go-lucky, filthy rich and not quite cut from great champion cloth? Or is she bent on earning a place in the company of Martina Navratilovas and Serena Williamses and Justine Henins of the game?

This is not Roddick's tournament's to win, but it is Clijsters'. How she fares will go a long way toward answering that question.

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