Sunderland held American striker Jozy Altidore out of Saturday's loss to Crystal Palace because of a hamstring injury.
Altidore will still travel to the United States for upcoming World Cup qualifiers against Costa Rica and Mexico. He will be evaluated when he arrives, a U.S. Soccer spokesman said.
With Altidore out and fellow forward Stephane Sessegnon dropped after his Tuesday arrest for drink-driving, Sunderland played Connor Wickham and Ji Dong-won but struggled to find any offense. Steven Fletcher came on for Ji at half-time and scored in the 65th minute but Sunderland lost 3-1.
The U.S., riding a 12-game winning streak, continues its World Cup qualifying in Costa Rica on Sept. 6, where it has never won, and then plays Mexico in Columbus, Ohio, on Sept. 10.
If Altidore is unable to play, it could open a spot up front for Aron Johannsson to play in his first competitive game with the U.S. Johannsson needed to appeal to FIFA to play for the U.S. because he had previously appeared in official games with Iceland's under-21 team. He made his debut with the U.S. in August in a friendly victory over Bosnia-Herzegovina.
U.S. coach Jurgen Klinsmann could also deploy Eddie Johnson or shift Clint Dempsey or Landon Donovan to cover for Altidore's absence.
Altidore has scored in five straight games for the U.S., including a hat trick against Bosnia.