U.S. coach Bob Bradley said he wasn't sure whether goalkeeper Tim Howard had broken his ribs in the match against England.
Howard collided with England striker Emile Heskey when Heskey's foot slid into him in the 29th minute of the match on Saturday.
"He'll be evaluated later today and then a decision will be made as to whether he'll need further tests," Bradley said Sunday. "Obviously he was sore - did a great job of taking a tough hit, and staying in it and playing really well. But we'll assess him later today and figure out then what we need to do from there."
Howard played the second half after having an injection of a painkiller and made six saves as the United States rallied for a 1-1 tie.
Bradley said it was too early to say Howard was doubtful for the game against Slovenia on Friday. "At this time I think there's no answer," he said. "But when you see the way Timmy handled himself after the collision last night, you'd certainly expect he'll be on the field again."