A lot of people are rooting for the U.S. -- not least the world's book-makers, who see American fans as a rich, untapped market.
"This is the single biggest betting event in history," says Jon Ivan-Duke of Britain's William Hill Bookmakers.
The World Cup is a bookie bonanza. Ivan-Duke says, "200 million pounds will be turned over this World Cup."
That's pushing 350 million dollars. And that's without the U.S., where betting is only legal in a few states.
If Americans can learn to love soccer, the bookies are betting they can learn to love putting a few bucks down on the game as well.
"If those laws were to be relaxed across the states ... then we're ready and raring to go, really," explains Ivan-Duke.
In a statistics-mad country like the U.S., the bookies think their newest fad has "America" written all over it.
Nowadays, the betting doesn't stop when the game starts. One bookmaker even offered odds on whether Uruguay's Louis Suarez would bite someone -- and paid up when he did.
The biggest bet placed on the World Cup so far was from an American. "This particular customer in our Nevada sports book shop put a bet of $320,000 on Argentina to beat Iran," says Ivan-Duke.
In that game, Argentina won on a last-minute goal.
The current odds for the U.S. to win the World Cup are 80 to 1.