Despite arriving late to the U.S.'s opening World Cup game against Ghana and missing their first goal 29 seconds in, Vice President Biden stopped by the locker room to congratulate them on their 2-1 victory. (YouTube/The White House)

As the U.S. national soccer team turned attention from Ghana to Portugal, from the euphoria of a memorable finish on the coast to the gravity of a World Cup trial Sunday against the sport’s premier player in Amazonia, Jurgen Klinsmann prepared to go forward without his top-choice striker, Jozy Altidore.

Altidore strained his left hamstring in the first half of the Group G opener Monday. Instead of accompanying teammates to a conditioning session, he reported to a local hospital to undergo an MRI exam. Details were not immediately released, but even under the best circumstances, Altidore would almost certainly miss the final two Group G matches.

Starting defender Matt Besler also underwent testing for a less severe hamstring injury that sidelined him for the second half of the 2-1 victory. From all early indications, he will be available for the Portugal match.

Forward (and captain) Clint Dempsey suffered a broken nose during the match but played the full 90 minutes. He is also expected to be ready for Portugal, and may wear a protective mask.

Klinsmann tried to remain upbeat about Altidore returning at some point.

“We have to see how he reacts the next couple of days,” Klinsmann said. “We are full of hope still that he comes back in this tournament. How quickly, that is down to his healing process.”

Altidore is not as vital to the U.S. campaign as Michael Bradley and Dempsey, but he is the only pure target forward on the roster. He is a physical presence with the ability to hold the ball under pressure and occupy center backs, not to mention provide menace in the penalty area — as Altidore did with a pair of goals in the final tuneup less than two weeks ago against Nigeria.

According to teammates, Altidore was in tears as he was stretchered off the field. He had been seeking to have a more impactful World Cup after failing to score in the 2010 tournament in South Africa.

He was not made available to the media Tuesday. Speaking after the Ghana game, he said: “We’ll see what happens. I would love to [play], but what matters is the team.”

Altidore’s replacement, Aron Johannsson, did not have any impact on the Ghana match but didn’t receive much service either as the U.S. team struggled to maintain quality possession following Dempsey’s first-minute goal.

Klinsmann’s other reserve forward is Chris Wondolowski, but the decision of who to start alongside Dempsey is not as simple as choosing Johannsson or Wondolowski. Klinsmann may leave Dempsey as the lone forward and play five midfielders.

“They are guys who like to move off the ball a lot and do things,” midfielder Graham Zusi said of Johannsson and Wondolowski. “There are different ways we can use each other, depending on how we want to play.”

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With five midfielders, Jermaine Jones would return to his natural position in the middle — he was on the left Monday — and Klinsmann would employ two natural wide players.

Perhaps playing into the decision is the U.S. team’s standing in the group. With three points, the Americans are not desperate for victory, as they would have had they lost or tied Ghana. A draw with Portugal would keep them on course to claim one of the group’s two places in the knockout stage.

Not only are the Americans ahead of Portugal, which was throttled by Germany, 4-0, in its opener, they are well ahead in the first tiebreaker (goal difference).

Nonetheless, the Americans say they will not play conservatively.

“Does it go through our minds? I don’t think so,” midfielder Alejandro Bedoya said. “Based on past World Cups, sometimes four points isn’t even enough. We are aware of that as well, but I don’t think we’ve gotten that far to think, ‘Okay, if we get a draw then maybe we are safely through.’ We are going out against Portugal to win that game.”

Klinsmann never telegraphs his plans, but for now, he is looking for another three-point performance, which would all but secure passage to the round of 16. He is also well aware of Portugal’s personnel issues: Defender Pepe will serve a red-card suspension, defender Fabio Coentrao is out with a leg injury, and forward Hugo Almeida and goalkeeper Rui Patricio are ailing.

“We have the confidence now to go into that game and say, ‘We’re here, we’re here, we want to beat you. We want to get to the next round,’” he said. “Our approach is not to defend for 1-1 or nil-nil; we go there and we want to win this game.”

Klinsmann indicated he will have a full-strength back line. Besler came off with tightness in his right hamstring and is “no problem, all fine for the next game,” the coach said. Besler’s replacement, 21-year-old John Brooks, scored the winning goal in the 86th minute with a header off Zusi’s corner kick.

Asked whether the training regimen over four weeks contributed to two hamstring injuries in the first half of the first match, Klinsmann said: “It is a result of a physical game, very fast-paced, very demanding. Our preparation [since mid-May] went really well; we were lucky not to have any injuries. We slowed it down before that [Ghana] game, so everybody was fresh, everybody was good. And then you hit some individual cases.”

Bedoya also had physical issues — a hip pointer that has troubled him before and leg cramps — but is expected to be available this weekend.

As for putting the emotional victory behind them, the Americans say have begun honing in on Cristiano Ronaldo and Portugal.

“We only talk now how we can beat this Portuguese team,” Klinsmann said. “This is our goal. We believe in it. We believe we can go to Manaus and beat them.”