Goalkeeper Tim Howard believes the United States can continue to improve at the FIFA World Cup ahead of their last-16 tie with Belgium.
Jurgen Klinsmann's side came through a difficult group that included Germany, Ghana and Portugal to book a knockout-stage meeting with Belgium.
Belgium also come into the meeting in good form, having finished top of Group H with a 100 per cent record.
Howard feels the USA's performances thus far demonstrate the progress made under Klinsmann but knows they are far from the finished article.
"We're a younger team and I always say that youth brings hunger," he told FIFA.com.
"We've been playing some brilliant football.
"We've been able to open some teams up. We're not world-beaters yet, but we're standing toe-to-toe with some big teams."
The USA endured a nervy finale to the group stage before progressing on goal difference ahead of Portugal in third.
Everton keeper Howard feels their progression from a pool dubbed the 'Group of Death' shows the quality they possess.
"We navigated ourselves through the so-called group of death," he added.
"Not many people gave us credit to be able to do that before the tournament started."