Evans trained his calf two weeks ago and has missed the Seattle Sounders' last two matches. When he missed their match on Saturday, it looked likely he would have to pull out of the U.S. team, which he has done.
Jurgen Klinsmann will certainly be disappointed to lose Evans, who is likely the Americans' first choice right back at the moment. The friendly against Mexico was going to be an opportunity for Klinsmann to see his entire first choice defense together -- Omar Gonzalez, Matt Besler, DaMarcus Beasley and Evans -- but that will not be the case anymore.
While Klinsmann has called Beltran into the team, it's unlikely he starts in Evans' place. DeAndre Yedlin or Michael Parkhurst are better bets to get the nods, and it will be a huge opportunity for whoever Klinsmann tabs. Yedlin is a menace going forward and his defense is rapidly improving. There are questions about whether he's progressed enough defensively to handle the international game, especially in a World Cup, and this will be his chance to answer them, while Parkhurst is just 18 months removed from a Man of the Match performance at right back in a World Cup qualifier.
Evans may be the likely starter for the U.S. at the World Cup right now, but the spot is still very much in play. Geoff Cameron has been strong for Stoke City, although he has had trouble replicating that for the U.S., while Yedlin is making strides every week and Parkhurst is a steady, dependable option. Right back is a toss up and this injury just makes it possible for a couple more names to join the discussion.