Considering the speed, power and experience of the Portuguese attack, concerns on defense are greater for the U.S. than those on offense.
To that end, central defender Jeff Agoos has trained both in that position and at left back, in case Arena decides that Regis is not his starter. Also training at left back, although U.S. spokesmen declined to confirm it, has been Frankie Hejduk, who normally plays at right back.
Cobi Jones does in midfield.
"Frankie is a good one-on-one defender, with good quickness and defends very well off the ball," he said. "He is one of our better defenders. And in terms of one-on-one duels, he does a pretty solid job."
The U.S. team is scheduled to hold a closed-door practice at the Suwon World Cup Stadium on Tuesday night and, a team spokesman said, it is unlikely anyone will know Arena's starting lineup until an hour before Wednesday night's game.
By then, miraculous cures could have occurred--the World Cup being a prime stage for disinformation campaigns--or the American lineup could have an unfamiliar look.
"We have been so used to injuries that we have rarely played with our whole starting group over the last three years," Arena said. "One thing about this team is that we're always prepared to make adjustments. So in that sense we're comfortable.
"Would we like to have Chris Armas here? Yes. Not going to happen. Would the French like to have had [Zinedine] Zidane in the opening game? Not going to happen. Would the Brazilians like to have Emerson? I mean, it's all part of it. It's happening to every team. It's not just the U.S. team."
And is that troubling to Arena?
"No," he said. "I think I'll sleep pretty well tonight and tomorrow. I'm confident with our group of players, whomever has to play."
All the same, Portugal's Oliveira probably is sleeping even better.
Reyna, Mathis could miss U.S. opener
Key midfielder and forward nursing lingering injuries.
We've upgraded our reader commenting system. Learn more about the new features.