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USA coach Jurgen Klinsmann is certainly not lacking confidence at the moment after telling his players' families to change their flights until after the World Cup final.

Team USA faces a daunting encounter with dark horses Belgium in the knockout round, but after qualifying from a difficult group including Portugal, Germany and Ghana, optimism clearly surrounds Klinsmann's camp.

The former Germany forward, who won the World Cup with West Germany in 1990, certainly knows a thing or two about what it takes to lift the biggest prize in world football. Reuters reported U.S. defender Omar Gonzalez's comments on his 49-year-old coach:

Jurgen has been nothing but positive. He’s telling us, he’s telling our families to change our flights to July 14, 15, because we’re going to be here until the very end. So that just speaks volumes to how positive he is, how much he believes in this team, and obviously it trickles down to all of us. That means that we’re all as confident as he is, and that we all believe in this team. We plan on being here a few more weeks.

Jozy Altidore's status for the crucial encounter with Belgium is still uncertain, and his presence with the influential Clint Dempsey could be pivotal to their chances.

It has been an impressive campaign by Klinsmann's men, but his comments may be seen in some quarters as playful rather than serious optimism.

It's also worth mentioning he was previously criticised for taking a pessimistic tone on his side's chances in Brazil.

Belgium are likely to provide a stiff examination of the USA's credentials, however. The Belgians have enjoyed a renaissance under Marc Wilmots' tutelage and are many commentators' sleepers to storm to glory this year.

To borrow the most overused of terms, Belgium are enjoying a golden generation made up of the likes of Vincent Kompany, Thibaut Courtois, Eden Hazard, Romelu Lukaku, Kevin De Bruyne, Axel Witsel and Marouane Fellaini, among others.

Belgium will still need to have a bad day and the States an excellent one if Klinsmann's prophecy is to come true.

The sudden change in his attitude seems to have coincided with a recent wave of support for the United States at home and indeed in Brazil. As reported by BBC Sport's Ben Smith, the World Cup has seen records tumble for support from the USA.

It is estimated that nearly 25 million tuned in for their crucial clash with Portugal, and more than 100,000 U.S. fans have traveled to Brazil—more than three times as many as any other nation.

If Klinsmann has it his way, they'll be there for a little while longer at least.