American midfielder Josh Gatt injured a knee Saturday playing for Molde in its 3-1 win over Sarpsborg in the Norwegian first division.
Gatt was selected Thursday for the 23-man U.S. roster for next month's CONCACAF Gold Cup and was due to report next week to a training camp in San Diego.
U.S. Soccer Federation Michael Kammarman said Gatt will be evaluated Sunday.
The Americans can replace players up until 24 hours before their opener against Belize on July 9. Any replacement must come from among the 35 players on the preliminary roster announced May 31.