Sao Paulo - Jozy Altidore was due to have his injured left hamstring examined after the US squad returned to its Sao Paulo headquarters from Monday night's 2-1 victory against Ghana.
US Soccer Federation spokesman Neil Buethe confirmed that Altidore would be evaluated later Tuesday, as was expected.
In the first half Monday, Altidore ran down a ball with Ghana's John Boye when he lowered his head to attempt to control it and immediately grabbed the back of his left leg and fell to the ground in pain.
He was replaced by Aron Johannsson.
The Americans' next Group G match is Sunday at Manaus against Portugal, a 4-0 loser to Germany.
Central defender Matt Besler was replaced at halftime as a precaution with right hamstring tightness.