The New York Times has compiled the results of nearly 20,000 YouGov online interviews from 19 countries participating in the 2014 World Cup and the results are both fairly interesting and somewhat decieving. In response to the question of "Who will win the World Cup?" only four countries had themselves as the top answer: two-time World Cup winner Argentina, five-time World Cup winner and host nation Brazil, 2010 World Cup winner Spain and no-time World Cup winner the United States. Every other country had Brazil as the top response.
Now, the U.S. result should be qualified with the information that despite being the top response, only 14 percent of respondents actually said the United States would win and the second answer of Brazil had 10 percent. It's also unclear how many of those in the 14 percent said the U.S. because they actually believe it or because they had no idea what the World Cup is and figured their own country was the nicest answer. The next lowest top answer was in another large, diverse and still developing football nation: Australia, where 23 percent said Brazil and 10 percent said Australia would win.
When asked "Which team are you rooting against?" Again, the top answer in the U.S. was the U.S. — but only with a mere 5.4 percent of responses (and a 1.3 percent margin of error) and Russia a close second at 5.2 percent (again with a 1.3 percent margin of error). Despite the United States gifting Mexico with a place in the last-chance World Cup qualifying playoff against New Zealand, Mexico's top reponse to this question was still the U.S. with 16 percent, which shows that the rivalry and perhaps resentment of their northern neighbors outperforming them in recent years runs deep. It also might help explain why the top answer in the U.S. was itself.
The most decisive top answer to which team each nation will root against came in Japan, where 40 percent of respondents said South Korea. In South Korea, 38 percent said Japan (and 5 percent said South Korea). Eight of the 19 countries had the U.S. as its first or second answer (including the U.S. itself) in this category of small margins.
Anyway, the lesson here is probably that surveys with a relatively small sample size should be taken with a grain of salt.