U.S. center back John Brooks plays in Germany's top pro league and has even scored a winning goal in a World Cup match.
Still, the ferociousness of the competition in July at the CONCACAF Gold Cup surprised him.
"It was a completely different game," Brooks said. "Every game was like a war."
The U.S. performed unevenly in the regional tournament and suffered a disappointing semifinal exit against Jamaica, forcing the Americans into a playoff against Mexico next month for a place at the 2017 Confederations Cup.
As a result, Brooks and other players find themselves with two chances to impress in exhibitions against Peru on Friday night and Brazil on Tuesday night as October roster decisions loom.
"We want to hopefully give them as much exposure as possible and give them a chance to prove a point," coach Jurgen Klinsmann said, "even if it's in just a few minutes."
The stakes are especially high for Brooks and six other center backs who were called into a training camp that began Monday.
The U.S. allowed five goals in its six Gold Cup matches, a concerning number considering the Americans were favorites in all six contests.
"Competition is good," center back Matt Besler said. "It helps the team get stronger, and that's what we need right now."
Some of that seven-man contingent may see time at outside back in the exhibitions. But Klinsmann has said he would prefer to go with DaMarcus Beasley and Fabian Johnson at those wide spots next month, provided both recover in time from minor injuries.
That leaves two starting defensive spots up for grabs.
"Everybody wants to play, and I want to play, too," said Brooks, who added that Klinsmann tinkered with a range of partnerships at training this week.
The picture is only slightly less cloudy at forward, where two-time World Cup vet Jozy Altidore has returned after Klinsmann sent him home midway through the Gold Cup.
Clint Dempsey is expected to join the squad after Friday's game and would likely start against Mexico.
As for the second attacking spot, Klinsmann appears to be considering options. He even called in Andrew Wooten, who plays in Germany's second division and at age 25 is in his first national team camp.
The U.S. scored just once on 10 shots on goal in its semifinal loss to Jamaica.
"We had enough chances to put the game away," Klinsmann said. "We needed to put the ball in the net with the occasions we had in that game."