USA forward Jozy Altidore gestures in pain during a Group...

USA forward Jozy Altidore gestures in pain during a Group G match against Ghana at the Dunas Arena in Natal during the 2014 FIFA World Cup on June 16, 2014. Credit: Getty Images / Javier Soriano

The United States will have to go to Plan B, C or even D when its worst fears were realized Thursday as striker Jozy Altidore officially was ruled out of Sunday's World Cup match with Portugal.

U.S. Soccer officials could not say for how long the 24-year-old would be sidelined with a strained left hamstring, although spokesman Michael Kammarman said the team was "hopeful that he will be available for the tournament."

Altidore was with the team at its Sao Paulo FC training facility for conditioning and treatment. It was not known what grade the injury was and whether Altidore would travel with the team to Manaus.

"It's bad news but I think the team will handle it," midfielder Jermaine Jones said. "We have to step on it."

Center back Matt Besler (right hamstring tightness) and captain and striker Clint Dempsey (broken nose) were cleared to play, although the latter had not decided whether he was going to wear a mask.

"It's not required," Kammarman said. "We travel with masks. You can do custom masks."

Losing Altidore, who was rounding into form after a horrendous personal scoring drought, was the only blight from the Americans' 2-1 win over Ghana on Monday.

"He's a big player for us," midfielder Kyle Beckerman said. "We all came into this World Cup thinking 'This is going to be a huge World Cup.' You know, he got two goals before we took off, so we're extremely bummed for him."

USA coach Jurgen Klinsmann, who was not available for comment, has several options -- including using Chris Wondolowski or Aron Johannsson in Altidore's place or utilizing a formation that would deploy one striker and five midfielders instead of the usual two forwards and four midfielders.

"We'll see what we decide to come out with," Beckerman said. "Any formation we play it's going to take an effort from everyone, it's going to take everybody watching each other's backs."

Wondolowski has forged a reputation as a poacher for the San Jose Earthquakes in the MLS. Johannsson, who plays in Iceland, replaced Altidore when he went down in the 18th minute against Ghana and wasn't much of a factor.

"He can score from anything," Beckerman said of Wondolowski. "He can score when you think there's no chance and then next thing you know he scores. He plays defense. He works his tail off for the guy behind him. He does a lot of things that don't show up on the stat sheet."

Beckerman added Johannsson was "crafty. He's really tricky with the ball. They both have some pace that can get away and get their shot off from nothing as well."

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