SAO PAULO, Brazil – If someone wants to publish a German version of "The Power of Positive Thinking," Jurgen Klinsmann is a likely candidate to be the author.

Regardless of how dire the situation, whatever criticism he is under, the U.S. national coach always seems to be smiling and forever optimistic.

That was in contrast to headlines Klinsmann made several weeks ago when he said the Americans could not win the World Cup.

U.S. Soccer President Sunil Gulati claimed those comments were so un-Klinsmann-like.

"He exudes confidence," he said. "The comments he made about we can't … that's not what he believes, that's not the sort of guy he is. I walk into a room with Jurgen when we talk to him and you come out of that room believing that you can win the World Cup. He never says you're going to win the World Cup, but he's so confident about it. That's extraordinary. That fits with the American mentality, which is, 'We can.' "

The Americans have surprised the pundits by surviving the Group of Death and reaching the Round of 16.

Some observers interpreted those original Klinsmann comments as keeping the bar low.

But Friday, he made a major about-face when he threw out a challenge to his team: Think big, think even the championship game.

"If everybody goes to their own personal limits in the context of the team, we're going to go further in this tournament," Klinsmann said. "You've got to realize that moment. So I asked all of the players to make sure their flights are booked for July 13. That's how you have to approach a World Cup. Always start with the end in mind. The end is July 13."

That is the date of the final in Rio de Janeiro.

Klinsmann's optimism was in overdrive as the Americans started preparation for their Tuesday encounter against Belgium in Salvador.

"It just gives you more hunger for the next step," he said. "This is now what we need. We want to have those benchmarks. We want to be one day in the top 10, top 12 in the world. So if you want to be there one day, this is now the moment to prove it, this is now the moment to show it. I told the players that this is now the time you've got to step it up."

Klinsmann is more than a cheerleader as he drives his team in practice.

"He wants to play at a high level," veteran left back DaMarcus Beasley said. "He demands a lot out of us. Always makes us be on our toes for games. He also demands that perfection out of the players."

Klinsmann's reputation precedes him. As a player, he won a World Cup, with West Germany in 1990. As a coach, he directed a young German team to a third-place finish in 2006.

"He's a player-coach. He understands the players' needs," Beasley said. "He's a guy who is very enthusiastic about the game, still. I know he wishes he probably can still play. At the same time, he has given us his wisdom. He's very confident when he coaches. We listen because he knows what he's talking about and we can learn a lot from him."

That confidence has gone a long way with an underdog U.S. side.

"It's big kudos to him," central defender Omar Gonzalez said. "If you're going into games thinking you can't win, then you're probably not going to win. He puts all his faith in us. He gives us all of the confidence in the world. We believe we can step onto the field with any team and beat them."

Klinsmann's enthusiasm has been evident after the final whistle, as well. After the U.S. defeated Ghana, an exuberant Klinsmann pumped his arms, urging American fans that they should continue their cheering.

"This is a special time with Jurgen," Gonzalez said. "With Jurgen being so positive, being a big sparkplug is definitely unique."