PRINCETON, N.J. — Prove it.

Before the U.S. team tries to establish itself on soccer's biggest stage, several players must prove themselves worthy of being on the squad that goes to South Africa.

Sure, there are the givens — Landon Donovan, Clint Dempsey, Tim Howard, Jozy Altidore — who, if healthy, not only will make coach Bob Bradley's 23-man squad, but almost surely will start on June 12 against England.

There are quite a few uncertains, though, starting with midfielder DaMarcus Beasley and striker Edson Buddle. And they understand their tenuous situations.

"I'm old enough to know what goes into this and what I can and can't do," Beasley said Tuesday after a rainy practice session punctuated by running — lots of running. "Obviously I have to be myself and express myself well on the field and not make myself seem silly with what I do out there."

For Beasley, it's a strange place to be. A rising star for the 2002 World Cup, when the Americans made the quarterfinals, he was a mainstay heading to the 2006 tournament. Then Beasley's career went into decline just as the U.S. squad was falling apart.

Beasley became almost a forgotten man following his poor play at last year's Confederations Cup. Only recently has he emerged from that funk as he's bounced from England to Scotland and fought off injuries, including a thigh problem that sidelined him for two months this season with Glasgow Rangers.

He was recalled for a friendly at the Netherlands, and his free kick set up the only U.S. goal in a 2-1 defeat. With his performances improving, Beasley got the invite to this training camp.

"People know what I can do," he said. "Bob knows what I can do. It's just a matter of doing it."

Donovan believes Beasley, who will turn 28 on Monday, still can do all of the things that made him such a standout years ago.

"In Holland in March, we saw the DaMarcus we know," Donovan said. "I think that something has clicked in his head and he's figuring out now what it takes to be an elite player and we're seeing it again."

Donovan also has a strong connection with Buddle, his teammate on the Los Angeles Galaxy in MLS. Buddle has been a scoring machine for the Galaxy this season, prompting his invitation to the camp. He's not even listed in the 2010 team media guide, showing what an outsider Buddle has been in the U.S. national team's thoughts.

Buddle played 11 minutes for the U.S. team, back in 2003 against Venezuela. Yet he might need to demonstrate less to make the final 23-man roster than does Beasley, because the 28-year-old Buddle has a knack few other Americans can claim: a natural touch near the net.

He's scored nine goals already in MLS, but realizes the level of competition is about to rise exponentially.

"I have to compete hard with this opportunity," Buddle said as he ducked raindrops. "I need to combine well with the players we have on the field. And do it quickly.

"I've got to be coachable. I have to listen and learn and play my part."

Again, Donovan provides perspective on Buddle's challenge.

"The goals he's been scoring have been impressive," Donovan said, "but the things he's doing otherwise have been impressive, too. You just tell the guys coming into camp to keep doing what you're doing well. For the most part, he just needs to be himself and he'll be fine."

Also needing to re-establish their credentials will be players fighting back from injuries: forwardds Brian Ching and Eddie Johnson, and even Oguchi Onyewu, the long-time centerpiece of the back line. Bradley isn't about to take anyone who can't show he will be 100 percent fit for the World Cup.

The coach admits that "DaMarcus is a tricky one." Beasley hopes to provide some of that old magic for the coaching staff.

"I didn't communicate with Bob, so I was kind of like a kid waiting to see if he would be invited to make the team," Beasley said. "I want to make him see something in me that will make the decision hard."