USA midfielder Jermaine Jones will not face Panama in the teams' Hexagonal match in Seattle on Tuesday.
The Schalke player was subbed off on Friday in the USA's 2-1 win over Jamaica with what was later diagnosed as a mild concussion, and was considered unlikely to feature for his team on Tuesday.
Jones missed USA training on Sunday night, and then posted the following message on his official Twitter account, @Jermainejunior:
"Training today on bike!! Tuesday I'm out for the game against panama !!!"
With Jones out, the USA could turn to Geoff Cameron to fill the center midfield slot. The Stoke utility man came on for Jones in the Jamaica match. Other options include Joe Corona, Sacha Kljestan and Stuart Holden.
The USA faces Panama on Tuesday at CenturyLink Field, before travelling to Salt Lake City to face Honduras on June 18.