- The match will feature superstar Cristiano Ronaldo
- Ronaldo is grappling with a left knee injury
- The USA and Portugal will face off in notoriously humid Manaus
- A loss to USA would mean elimination for Portugal
Before the match even starts, there's already one clear winner in the U.S.-Portugal match Sunday: American sports bars.
Sure, they may be teeming with Americans who didn't know anything about the World Cup before USA's stunning victory over Ghana last Monday.
But Sunday's game has enough drama and story lines to excite both fair-weather fans and diehard followers.
Behold ... Ronaldo
Any confidence gained by beating Ghana will be tempered when USA faces Portuguese superstar Cristiano Ronaldo.
U.S. goal keeper Tim Howard is bracing for a serious challenge.
"He's the best in the world with the ball at his feet, good striker, left and right foot, dominant in the air ... the list goes on and on," Howard told reporters Saturday.
"We're going to do the best to bottle him up."
But even Ronaldo has an Achilles' heel -- or in this case, knee.
The 29-year-old injured his left knee in the opening game against Germany. Portugal suffered a stunning 0-4 loss.
But there's more to the team than just Ronaldo.
"Portugal is not only one player ... they have a lot of good players, and we have to be completely 100% with the whole team to stop this team and to win that game," U.S. midfielder Jermaine Jones said.
"Group of Death"
If USA wins Sunday, it's guaranteed a spot in the next round. If it draws or loses, the team still has one more game to try to escape the so-called "Group of Death."
The Americans will have to play without Jozy Altidore, who will sit out because of his strained left hamstring.
But the Portuguese have their backs against the wall. A loss to the Americans would eliminate Portugal.
Rumble in the jungle
As if both sides didn't have enough challenges, they'll be playing in a giant sauna.
Sunday's match will be in Manaus, a notoriously hot and muggy city in the Brazilian jungle.
But U.S. coach Jurgen Klinsmann said he's not too worried.
"We are thrilled to be here in Manaus. We're thrilled that this game is coming closer and closer," he said. "I think we were very well prepared for this climate here. We have similar climates to play in."
Howard said he hasn't prepared any differently for the game in Manaus.
"I think we're fit and we're conditioned," he said. "As long as we've got good sleep and we stay hydrated, we should be fine."