The USA are upset with their winner being disallowed against Slovenia yesterday.
The US went 2-0 down but fought back before Koman Coulibaly - taking charge of his first World Cup game - ruled out Maurice Edu's 85th-minute volley.
"I'm a little gutted," said Landon Donovan. "I don't know how they stole the goal from us. I'm not sure what the call was."
Coach Bob Bradley said: "I still don't know why the goal was disallowed."
Bradley added: "This team still understands how to fight for 90 minutes. This is something we've seen time and time again.
"It is important to understand that the players put a lot of emotion into the game and now they want a fair outcome."