[USA 30] On the opening day of the USA's pre-World Cup training camp at Princeton University, as much attention was on who wasn't on the field as was who was there. Considering Oguchi Onyewu, scheduled to arrive from AC Milan on Tuesday, hasn't played a game in seven months, the news that three other regular center backs didn't take part in full training on Monday wasn't good, but Coach Bob Bradley said it was too early to be concerning.

Watford's Jay DeMerit (abdominal strain) and fellow center back Chad Marshall (slight hamstring strain) sat out Monday along with goalie Tim Howard (quadriceps strain).

Tuesday Update: DeMerit and Marshall worked with trainers and did not take part in the full workout.

Carlos Bocanegra, who played on the left side and in the middle of the backline in qualifying, missed the last three weeks of the French season at Rennes, is recovering from an abdominal strain of his own, and worked on the ball by himself on Monday.

"Carlos did the warmup with the team today, a little bit of ballwork, individual work," said U.S. coach Bob Bradley, "and so he is making good progress."

The only other regular central defender in the USA 30 is Clarence Goodson, who like Onyewu, was en route from Europe.

Outside backs Jonathan Bornstein and Jonathan Spector have both been used (sparingly) in the middle of the U.S. defense, while midfielder Maurice Edu played at center back for the USA at the 2008 Olympics.

Like Marshall, Eddie Johnson has a slight hamstring strain and worked out on his own.