The United States were set to play Argentina on Wednesday, but they will not play because of excessive rain in Brasilia. As of now, the match is listed as postponed, which means they intend to reschedule it and play.
Looking at the photos, it's tough to imagine them being able to play today or tomorrow. Rain is hammering the Brazilian city and the forecast projects it to continue through tomorrow. The pitch is flooded and a moat has built up in the players tunnel, so the stadium not nearly fit to host a match.
The match is part of the Brasilia International Tournament. The U.S. opened the competition with a draw against China and then lost to Brazil. Argentina was their final group stage opponent and they still had a chance to make the Championship Match on Sunday.
Whether the U.S. finished in the top two and played in the Championship Match or had to play for third place, they were still scheduled to have a match on Sunday. Now the tournament organizers have to figure out how to fit in the Americans' match against Argentina and then the Championship and Third Place matches. That's going to be tough and if they have to cancel any, that won't bode well for a U.S. team that is struggling and needs more reps.