The versatile Sounders midfielder has started the USA's last three World Cup qualifiers at right back, but will play no part against Costa Rica and Mexico.
The U.S. federation announced on Twitter that the team's current starting right back will miss both World Cup qualifiers with a calf strain he suffered while playing for the Seattle Sounders against the Columbus Crew on Saturday night.
Evans has been replaced on the roster by Michael Parkhurst. The 29-year-old had a solid Gold Cup with the USA this summer, but has struggled to see the field with club side FC Augsburg in the Bundesliga. He made just two league appearances with the team after joining last year in midseason, and hasn't made a game-day roster in the league in 2013-14.
With Evans sidelined, the U.S. is likely to turn to Geoff Cameron at right back. The former Houston Dynamo man has been a starter at right back for club side Stoke City since joining last season.
Altidore suffered a hamstring injury last week, and will be evaluated this week to determine his status. The USA faces Costa Rica in an away Hexagonal match on Friday before returning home to face Mexico in Columbus four days later.