SAO PAULO -- The starting lineup will be different. That much is guaranteed after U.S. striker Jozy Altidore was ruled out for Sunday's match against Portugal (6 p.m. ET, ESPN/WatchESPN), but it might be the only certainty.
How coach Jurgen Klinsmann chooses to replace the big forward up top is an open question. And it might not be the only change he makes.
First, the formation. Two weeks ago, before the Yanks' final pre-World Cup warm-up match versus Nigeria, the coach argued that too much emphasis is placed on how teams line up.
"It doesn't really matter what shape we have, what system we have," Klinsmann said then. "It matters how we connect with one another on the field."
He's right, of course, but there's no question that Altidore's absence because of a strained left hamstring will force the coach to adjust his tactics, whether it's Aron Johannsson or Chris Wondolowski -- or neither -- who is chosen to lead the front line.
"Both of us have different styles than Jozy," said Johannsson, who struggled as a sub against a physical Ghana side, but who matches up better against the more methodical Portuguese, said Friday before the team flew to Manaus. "If either one of us gets on the field, then we'll just try to play our game."
If there's a favorite between the two, Klinsmann isn't tipping his hand. Sitting next to Johannsson as he spoke Friday was Wondolowski, one of three players made available at Sao Paulo FC's training facility (Michael Bradley was the other). It was the San Jose man who started alongside captain Clint Dempsey in an early-April friendly versus Mexico, a game in which he scored an opportunistic goal off Bradley's pass.
There's also an even chance that both backup forwards remain on the bench, with Clint Dempsey alone up top.
There will be significant risk involved if Klinsmann goes that way; Dempsey will be at least somewhat limited by the broken nose he sustained against the Black Stars, and he hasn't been particularly effective as a point man, even when 100 percent healthy.
Either way, tweaks are also possible elsewhere. Alejandro Bedoya picked up a hip pointer against Ghana, potentially opening the door for Graham Zusi to step in for him on the right wing. He could start regardless, should Dempsey lead the line, in a five-man midfield designed to frustrate the Portuguese and limit service to Cristiano Ronaldo.
Even the backline could see a switch. Klinsmann was almost too quick to label central defender Matt Besler "all fine" on Tuesday, less than 24 hours after he'd been pulled at halftime of the Ghana match with a tight right hamstring, and before the results of Besler's MRI exam were even known.
Minutes later, Klinsmann admitted that he hoped to keep Portugal's scouts guessing. So don't be shocked if youngster -- and Monday's hero -- John Brooks is in Besler's place when the lineup sheets come out about an hour before Sunday's match.
One player whose spot should be safe, though, is left back DaMarcus Beasley, who was criticized by some for his performance against Ghana. But as Besler explained afterward, the Yanks' game plan involved conceding the wings, and while the four-time Cup veteran Beasley bent at times, he never broke.
Besides, Klinsmann has plenty of other moves to consider between now and Sunday. That much is guaranteed, too.
Doug McIntyre is a staff writer for ESPN The Magazine and ESPN FC. Follow him on Twitter @DougMacESPN.