Christian Pulisic had to be replaced at half-time for the USA in their final group game against Iran on Tuesday night.
The Chelsea forward suffered an injury as he netted the opening goal for his nation and the first at a World Cup for the 23-year-old. Despite missing the second half, the USA held out to qualify from Group B setting up a last-16 tie with the Netherlands on Saturday.
He was replaced by Leeds United forward Brenden Aaronson for the second period. It is still unclear the extent of the injury and whether it could rule him out of further games in Qatar should the USA progress from Group B. The American has struggled with injury issues since joining Chelsea in 2019 from Borussia Dortmund.