NEW YORK -- Andre Agassi was trading practice shots with Yevgeny Kafelnikov in 90-degree heat under a midday sun.

Along the edges of the court and in parts of the stands at Arthur Ashe Stadium, workers were hammering and drilling, putting up signs and setting up electronic equipment.

Agassi's game long ago ceased being that sort of work-in-progress.

"I'm just trying to get better as an all-around athlete at this point,'' he says. "At 32, I'm not going to make real changes, although you're always tweaking.''

When the U.S. Open starts Monday, the sixth-seeded Agassi will be among a group of contenders aiming to take the title from defending champion Lleyton Hewitt.

In women's tennis, discussion of challengers for the year's last Grand Slam title pretty much begins with one name: Williams.

Not so with the men.

"It looks like there's a bunch of guys who could come out of the woodwork,'' CBS and USA analyst John McEnroe says. "There's total openness in men's tennis now.''

Indeed, when the top-ranked Hewitt won Wimbledon in July, he ended a stretch in which eight men had won the preceding eight major championships.

Unheralded players such as Albert Costa and Thomas Johansson (who withdrew from the U.S. Open with a shoulder injury) emerged to add "Grand Slam champion'' to their resumes.

It's awfully tough to handicap the Open, with Hewitt, two-time winner Agassi, 2001 semifinalist Kafelnikov, '00 champion Marat Safin, No. 3 Tommy Haas and No. 11 Andy Roddick all boasting games that could take them to the title.

And then, of course, there's Pete Sampras.

He's struggled through a disappointing year with a 20-16 match record and early exits from Grand Slam tournaments.

Sampras keeps changing coaches, has talked about switching to a different kind of racket, and has generally seemed more out of sorts on court than ever before.

"He's obviously playing with as little confidence as he's had probably his whole career,'' says McEnroe, who won seven major singles titles, including four at the Open. "I still don't believe that he's ready to throw in the towel. He could still do something.''

For all his problems -- more than 30 tournaments without a title since he won his 13th Grand Slam event in July 2000 -- Sampras has played superbly at the last two U.S. Opens.

He reached the final each time, and last year's run included consecutive victories over past champions Agassi (in a four-tiebreaker thriller), Safin and Pat Rafter.

"My goal is to win another major and I believe I can in this year's U.S. Open, even though I haven't shown much this year,'' Sampras says. "When I didn't play well five years ago, I could still win. That's not true today.''