New England defender Kevin Alston has strained his left hamstring while training with the Revolution and will miss the start of the U.S. national team's training camp Thursday ahead of a Feb. 24 exhibition against El Salvador.

Alston had a similar injury during last month's camp.

D.C. United goalkeeper Troy Perkins and midfielder Chris Pontius were delayed traveling to California because of a snow storm on the East Coast. They are not expected to report until Friday.

The team of all Major League Soccer players travels to Tampa, Fla., on Feb. 21 for the match. Europe-based players will be called in for a March 3 exhibition at the Netherlands, the last game before U.S. coach Bob Bradley picks his 23-man World Cup roster.

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