USA head coach Mike Tolkin praised Scotland's second-half performance as his men went down to a 39-16 pool loss at Elland Road, Leeds on Sunday.
The Eagles were 6-13 in front at the turnaround thanks to a close-range try from tighthead prop Titi Lamositele and the boot of in-form fly-half AJ MacGinty.
But after the break Scotland found top gear and ran in five second-half tries to win the game, with Tolkin quick to applaud his opponents' excellent turnaround.
"Credit to Scotland in the second half. For a team which is tired and which played four days ago, they came out with a lot of energy in the second half when the game was in the balance," he said.
"We knew it was important to come out of the clubhouse and establish ourselves and to get territory, but the opposite happened and after that we seemed to be constantly playing from penalties or playing from out of our own end, and it became difficult and frustrating with dropped balls at key moments. Any momentum we had was stopped and we played a lot from deep."
On the USA's performance in the World Cup so far, Tolkin lamented his side's hot and cold form as being their downfall.
"We've been inconsistent. We've had some flashes of very good play, some dominant play and physicality both on defence and attack and had injections of adrenaline. But at some parts we've made technical errors and had a lack of discipline," he added.
"A lot of these guys don't play the grind of a professional season with a hard game week in week out. So for some of our guys it's a real challenge and it's something that we have got to overcome."