US skipper Claudio Reyna strained his hamstring in the loss to Morocco and will await an MRI.
Manchester City’s Claudio Reyna went off injured in the 16th minute as the USA were beaten 1-0 by Morocco in a World Cup warm-up in Nashville.
The USA captain suffered a hamstring strain, but is hopeful of being fit for the tournament in Germany next month.
Reyna told ussoccer.com: “I’m going to get an MRI, it is close to the games, so obviously it is not the best timing but I’m hoping I’ve gotten away with something very minor.
“I’m optimistically thinking that it is not going to be something long term, but tomorrow I will know better.”
Mohamed Madihi beat Borussia Moenchengladbach goalkeeper Kasey Keller in the final minute to stun the 26,141 fans at the Coliseum in Tennessee.
The USA are in Group E alongside Italy, Ghana and the Czech Republic.