Updated

PRINCETON, N.J. (AP) — Before wrapping themselves in the red, white and blue, the U.S. soccer players surrounded themselves with orange and black.

Players began training for the World Cup on Monday at Princeton University's Roberts Stadium, a $13.4 million soccer facility opened two years ago by the alma mater of U.S. coach Bob Bradley, who also coached the Tigers from 1984-95.

Even on the first day of workouts, there were injuries that caused goalkeeper Tim Howard (quadriceps strain), defender Jay DeMerit (abdominal strain), forward Eddie Johnson (hamstring strain) and defender Chad Marshall (slight hamstring strain) to be in the trainer's room instead of sprinting across the lush, green grass, where pennants making Ivy League titles and NCAA tournament appearances flapped. Defender Carlos Bocanegra (abdominal strain) did ball work on his own.

"We've had long seasons, all of us, and guys have some knocks," said Howard, the starter for Everton in England. "There's no reason to rush anyone into it right now. Everything is just precautionary."

Landon Donovan, Edson Buddle and Jose Torres weren't around at all, off getting physicals after reporting Sunday. Four players based in Europe were still due to arrive late Monday or Tuesday.

And there were still questions about one player who won't be coming, forward Charlie Davies.

Davies thought he recovered sufficiently from a near-fatal car crash last October to merit an invitation only to learn last Tuesday he had been omitted from the 30-man preliminary roster.

Bradley said he made the decision based on input from U.S. trainers and the staff of Davies' French club, Sochaux. Bradley even viewed a video of Davies in a recent training session in France.

He understood Davies' anger last week.

"There's a lot of emotion at that time," he said. "From right after the accident until now, you know, he put all his energy and emotion into his rehab, and he did it, you know, with an obvious timetable."

Bradley shared a conversation he had with Davies in February, saying he felt as if he were a father or an older brother. He had been aware of all the favorable accounts Davies had been giving of his rehabilitation during interviews and on his Twitter account.

"I told him that I felt that if he could keep his attitude, his mentality, his work ethic, that that was going to be very important." he said. "But I also said if you can find a way to work and put everything into it and maybe not have so much to say, I think it would work for you. Because you don't want to put yourself in a position that you're making all this progress and yet somehow it seems like a failure because the timing just doesn't coincide with the World Cup. What's most important is that you can still get yourself back to the level that you were playing before the accident."

As for the group that's here, Bradley isn't worried — just yet — about the injuries. But he will keep watch.

"We assess as we go through this week whether some of the issues are already on their way to being better and guys are back in training," he said, "or whether it then becomes more of a concern."

Defender Oguchi Onyewu, due to arrive Tuesday, may be the biggest uncertainty, but Bradley expressed confidence in his fitness. Onyewu hasn't played since Oct. 14, when he tore his left patellar tendon. He ended the reason in regular training with AC Milan, which announced Monday he was extending his contract by one year through June 2013 — at no extra money.

"This is an exemplary gesture which deserves sincere congratulations," AC Milan said on its website.

After joining AC Milan last summer from Belgium's Standard Liege, he played in just one competitive match for the Rossoneri, as a 60th-minute substitute against Zurich in the Champions League on Sept. 30.

He'll be tested in exhibitions against the Czech Republic on May 25 in East Hartford, Conn., and Turkey four days later in Philadelphia. Bradley hopes to trim his roster to the 23-player limit by the time the team arrives in Philadelphia on May 26.

"It's like anything else — you have a plan in your head, but then you have to be able to adjust at some points," he said.

The team leaves for South Africa on May 30 and has a final exhibition against Australia on June 5. All that is just to get ready for the opener against England on June 12, followed by first-round games against Slovenia (June 18) and Algeria (June 23).

Bocanegra said that following the first-round elimination in Germany four years ago, reaching the second round is the expectation of fans, media — and players, too.

"We need to be getting out of the group stages on a consistent basis," he said.