Andy Roddick's nemesis -- Roger Federer, the one riddle he has yet to solve on a tennis court -- isn't here.

Nor is the next-best American tennis player, Andre Agassi, who withdrew from Washington's Legg Mason Tennis Classic on the eve of the tournament, citing the need to recuperate after winning his first title of the year Sunday in Los Angeles.

No matter. Roddick has not returned for his fifth appearance in Washington's hard-court event to defeat anyone in particular. He is here to build toward a moment. And whether he succeeds won't be clear for another six weeks, when the U.S. Open champion is crowned.

"The whole goal is to play well at the Open," said Roddick, who will play tonight. "It's to try to find my game over the next couple of weeks and find a comfort level and really hit my stride."

Since winning the 2003 U.S. Open at age 21, Roddick has devoted himself to becoming better. He has been rewarded on a scale that most pros only dream about -- hovering among the top three in the rankings, amassing 18 singles titles and nearly winning Wimbledon, falling to Federer in the last two finals.

But what Roddick wants most -- a second Grand Slam title, followed by a third, a fourth and certainly more -- has eluded him. And that's what is driving his frenetic summer schedule, which takes him from Washington to Montreal to Cincinnati for three weeks of hard-court play before heading to New York for the season's final Grand Slam event.

Asked to assess his chances at the U.S. Open, Roddick quipped, "As good as anybody not named Roger."

Roddick is hardly the only player to be undone by Federer's mastery of the game, particularly on grass. But his losses have drawn the biggest headlines because so much has been at stake in their meetings. It is scant solace.

"I'm not happy with the fact that there's someone out there who's better than me right now," Roddick said. "I'd like more than anything to have a Wimbledon title under my belt. But at the end of the day, I came out of that [2005 Wimbledon final] thinking, 'Okay, I played pretty well, and I got beat.' If anything, it just makes me work harder."

After a break to relax, Roddick returned to competition July 19 in Indianapolis, where he lost in the quarterfinals to fellow American Robby Ginepri. He says now that he wasn't prepared, mentally or physically. So Roddick's work begins in earnest at the William H.G. FitzGerald Tennis Center tonight, when he will face Ecuador's Giovanni Lapentti. If the tournament follows its seeding, he would then face Argentina's Juan Ignacio Chela, followed by Max Mirnyi of Belarus, and Britain's Tim Henman en route to Sunday's final.

Agassi's withdrawal leaves Radek Stepanek the highest seed (4th) in the other half of the draw.

Agassi informed tournament officials of his decision by fax Sunday night, shortly after defeating Gilles Muller in the final of the Mercedes-Benz Cup. "Over the years I have been privileged to be a part of the Legg Mason," Agassi wrote. "However, at this point in my career, I have to be extremely selective about the amount of matches that I play in preparation of the U.S. Open. I am sorry that I will not be there this year, but hope to return in 2006."

Agassi, 35, has been hobbled by flare-ups of a sciatic nerve in his lower back. The injury led to his first-round defeat at the French Open in May. After taking two months to recuperate, he returned to competition last week and was in dazzling form in defeating Muller, 6-4, 7-5, for his 60th career title.

Tournament chairman Donald Dell called Agassi's withdrawal unfortunate but understandable. "We are very appreciative of his participation and loyalty to the event every year since 1990," Dell said in a statement. "After winning the Mercedes-Benz tournament in Los Angeles this weekend, Andre feels he needs to rest, and we certainly understand that his health has to be his first priority."

Roddick, meantime, has made improving his net game his priority.

"Andy, for the most part, needs to be the one who is dictating the play," explained his coach, Dean Goldfine, while scouting potential second-round opponents. "He needs to use his forehand [his most powerful weapon, apart from his serve] to try and get his opponent out of position and then close off the points at the net."

The upside of attacking the net is two-fold: It forces opponents into low-percentage shots, and it shortens the points, which saves wear on the body. But like all players whose confidence lies on the baseline, the hurdle for Roddick has been finding the resolve to come to the net at critical junctures, when things look most bleak.

"That's the hardest thing for everybody -- doing something that you're not totally comfortable doing and you don't have as much confidence in when you're at 4-all in the fifth set," Goldfine said. "That's what you're seeing out there: It's like growing pains."

Should Roddick win the Legg Mason while taking that next painful step, so much the better.

"Nothing breeds confidence like winning and being successful when you're working on things," Goldfine said. "A lot could be accomplished by coming out here and winning this tournament. That could really help Andy move along in the progression."

"I'm not happy with the fact that there's someone out there who's better than me right now," said top-seeded Andy Roddick, above, referring to his arch rival, Roger Federer.