SAO PAULO -- U.S. coach Jurgen Klinsmann is confident that striker Jozy Altidore can still play a role at this World Cup despite the strained left hamstring he suffered in the first half of the Americans' 2-1 win over Ghana on Monday night.

Altidore had an MRI on his hamstring on Tuesday, and Klinsmann said the team would watch how he responds this week.

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"We've got to see how he now reacts the next couple of days with his hamstring, and we're full of hope that he comes back still in the tournament," Klinsmann told reporters at a Tuesday news conference held at Sao Paulo FC's training facility, the Yanks' home base while in Brazil.

"That's what we're going to work on every day. The medical staff is doing a tremendous job [for] weeks, so we still have the hope that Jozy will be back. How quickly, that is down to his healing process."

In the first half on Monday, Altidore was running down a ball with Ghana's John Boye when he lowered his head to attempt to control it. He immediately grabbed the back of his left leg and fell to the ground in pain. He was replaced by Aron Johannsson.

"Obviously we all hope he'll be all right,'' midfielder Alejandro Bedoya said. "I'm sure if he's able to work hard we're going to get him back. We have players that can play different roles and come in and do a job. Last night we had two subs come in and add something to the game.

"Aron is a good player and I think he did well last night under the circumstances. It was hard to get him the ball."

Early on Tuesday, Altidore sent a message to fans on Twitter:

Thanks to all of you for the messages and well wishes it means so much to me. I love this team and our amazing fans. I believe.. #1N1T — Jozy Altidore (@JozyAltidore) June 17, 2014

Klinsmann also said defender Matt Besler, who exited the match against Ghana at halftime as a precaution after tweaking his hamstring, will return to play against Portugal in the Americans' next game.

"First info we have, Matt is no problem, all fine for next game," Klinsmann said.

Jozy Altidore has not been ruled out for the rest of the World Cup after injuring his hamstring on Monday. Robert Cianflone/Getty Images

Clint Dempsey is still deciding whether to wear a mask to protect his broken nose, though the U.S. Soccer Federation said he should be able to play despite the injury.

After the Ghana game, Dempsey was asked if he thought his nose had been broken by a first-half kick from Black Stars defender John Boye.

"I think so," he said, his nose clearly deformed as he spoke to reporters after the match.

On Tuesday, Dempsey's self-diagnosis was confirmed.

"Clint broke his nose," U.S. Soccer spokesman Neil Buethe said. "He's still trying to determine if he'll wear a mask, but it shouldn't affect him in any way."

Klinsmann said the decision on whether to wear a mask would be up to Dempsey.

"I don't know, maybe he has the option of getting a mask on," the manager said. "Broken nose or not, I don't know how much a mask can protect him. Whatever he feels good with.

"I think with a broken nose, yes. It was tricky during the game. He barely could breathe, he struggled with that. But once it's broken, it's broken. It will take time to heal completely. But unfortunately it's also part of our game. He's going to be all right."