Two hours after opening the World Cup, the United States could dream about defeating Portugal and world player of the year Cristiano Ronaldo.

The Americans' confidence is soaring from Monday's 2-1 win over Ghana, the team that knocked them out of the last two World Cups.

"Anything is possible in football," U.S. coach Jurgen Klinsmann said.

Trying to reach the knockout stage of consecutive World Cups for the first time, the Americans went ahead when Clint Dempsey scored 29 seconds in. The night ended with another adrenaline rush on 21-year-old John Brooks' 86th-minute goal, just four minutes after Andre Ayew had scored for Ghana.

Fast-paced end-to-end action in between included a broken nose for Dempsey and hamstring injuries to forward Jozy Altidore and defender Matt Besler.

"It showed our resilience. I thought our maturity was awesome," goalkeeper Tim Howard said.

Dempsey became the first American to score in three World Cups; a converted midfielder, he also became the first U.S. forward to get a World Cup goal since Brian McBride in 2002.

Brooks became the first U.S. substitute to ever score in 30 World Cup games over 84 years when he rose to head in Graham Zusi's corner kick from 8 yards. Brooks, one of the team's five German-Americans, fell to his knees and pushed his face into the ground, his hands on his head, overcome by his first international goal.

He thought back to two nights earlier.

"I told some teammates that I dreamed that I scored in the 80th minute and we won the game," he said. "And now it was the 86th minute, and we won."

He dreamed of scoring on a header.

From a corner kick.

Just liked it happened.

Now the U.S. is in good position in Group G, where Germany opened with a 4-0 rout of Portugal. After the game, Vice President Joe Biden visited the victorious Americans in their locker room.

"I just think it shows our character," Dempsey said. "We did a good job of grinding out the result. It's a huge three points for us."

Klinsmann had predicted this would be like a final. Altidore was hoping it wasn't his finale.

The forward was carried off on a stretcher after his left hamstring gave out in the 21st minute when he tried to control a long ball. He awaits tests that will determine whether he can return for this World Cup.

"I was sprinting and I felt something. We'll see what happens," said Altidore, who will have a scan Tuesday back in Sao Paulo. "I was crushed."

Dempsey went down, too, on a balmy late-autumn night. The U.S. captain ended the first half with a tissue up his nose to stop the bleeding after John Boye's shin to his face during a battle for a header in the 31st minute.

"I just had trouble breathing," Dempsey said through a swollen nose. "I was coughing up blood a little bit. Hopefully I'll be able to breathe through my nose again before the next game."

Klinsmann considered that knock minor.

"I broke mine three or four times and it's all right," he said. "We'll give him a few days."

Howard made several sprawling saves. The Black Stars had 59 percent possession and outshot the U.S. 21-8.

Besler felt tightness in his right hamstring, and Brooks entered at the start of the second half. Zusi came in for Alejandro Bedoya in the 77th minute.

Odds now favor advancement; 39 of 46 teams that won openers in the last four World Cups reached the knockout rounds.

Thousands of American fans who made the trek south of the equator left chanting the same words as when they entered: "I believe that we will win! I believe that we will win!"

But Klinsmann also was a bit wary of Portugal, next weekend's opponent in the rain forest capital of Manaus.

"I don't know how Cristiano Ronaldo behaves when he's angry," he said.