BUENOS AIRES, Argentina -- I do worry about Costa Rica.

As I aim for Brazil, I worry that if Costa Rica continues to add World Cup mirth to its already established status as the happiest country in the Western Hemisphere, it might lapse into immodesty.

I say this as a citizen of a country that practices a strikingly understated modesty. We Americans never express our patriotism with any volume. Give us some woodwork, we rush to blend into it. We are known around the globe for our quiet confidence, our restrained manner and our deference and knowledge about foreign lands, often expressed in our rampant multilingualism. If we wished, we could shout routinely a three-letter chant that would identify us as Americans, but we don't bother with that. We never assume our system or our country the best. Unlike Costa Rica, we have not abolished our military, yet very much like Costa Rica, we deemphasize our military, never interfering in the affairs of others and never suggesting to others that our values have supremacy.

As Costa Rica has become a World Cup titan, surviving a group with three nations that all have won World Cups, I fear that it might not follow our modesty model.

Of course, Costa Rica is charming-times-charming. It has reached the round of 16 with one group game to spare despite drawing talent from the world's 124th-ranked population at 4.7 million, roughly equal to South Carolina, in an area slightly smaller than West Virginia. It has gotten people, including American people, bragging about CONCACAF, when before you never really hear anybody bragging about CONCACAF, and you can spend years feeling generally glad you never really hear anybody bragging about CONCACAF. (Costa Rica finished second to the United States in CONCACAF World Cup qualifying, beating the U.S. 3-1 at home and losing 1-0 in the snow in Colorado in March 2013.)

This unnoticed bunch has loosed the following fabulousness from Jim White of The Telegraph in London, as he attended Costa Rica's 1-0 upset of Italy last Friday in Recife: "Back home in Central America the nation had, by all accounts, gone collectively doollaly as it marked the achievement, an entire population taking the day off work to party."

You're pretty special if you can make things go doollaly.

So the Costa Rican headlines have included "Sin Limites" (Al Dia, and meaning "Without Limits"), "History!" (La Republica), "How Do You Like Us Now?" (Tico Times) and, whoa, "The Giant of the Group of Death" (La Nacion). Yeah, that's right. They're running around calling Group D the "group of death," after we've spent six months moaning that it's Group G. They think their group is more deathly. It's not an encouraging signal.

Further, Costa Rica has forged this inversion of earthly reality: It has surged to two wins and its first knockout-round qualification with such dispatch that it has forced its Colombian manager, Jorge Luis Pinto, to reassure everyone that, get this, his team will try to win its final group match on Tuesday against England. He actually said, "It won't be easy; England will be very tough opponents."

A 2,500-to-1 shot at the outset reassures the inventor of the modern game.

That's a big sheesh if ever there were one.

If Costa Rica were not already a model for how to conduct a country, it would not run the terrible risk of becoming annoying to others. But no. It insists upon on a comprehensive lovability. In a recent video ad the government has sent around the world for tourism promotion, it takes eight seconds before you see a mind-bogglingly beautiful bird beak. There's a photo of a frog who apparently lives in Costa Rica, and this frog looks like the most pleasant, spritely being you'd ever want to meet, boasting orange hands and feet, red eyes, a green skin with some black thrown in because it just was not beautiful enough. The frog looks ludicrously happy, and no wonder, given that the Happy Planet Index just ranked Costa Rica No. 1 out of 151 nations studied.

The country hasn't even had an army since 1949, with no need, having exported to the world only pleasantness. When the national team upset Italy last Friday, the schools closed so the children could join the celebrations. Aw. The president, Luis Guillermo Solis, apparently went out and walked to the celebration, his security detail looking thin in his Twitter photo, his populace unthreatening given its capacity to spot drop-dead-gorgeous frogs on a regular basis. Aw, again. The CIA World Factbook refers to "Costa Rica's political stability, high standard of living and well-developed social benefits system," plus its "tremendous progress toward achieving its goal of providing universal access to education, health care, clean water, sanitation and electricity."

What ranked as the second-lead story Monday in the Tico Times? Holy lack of horror, it was an endangered green sea turtle with a tracking device. He successfully completed his journey from Costa Rica to the Galapagos Marine Reserve in Ecuador.

The turtle's name is Sanjay.

Apparently, he knew where he was headed all along.

Well, la deeee daaaa.

To top all this, there came Bryan Ruiz's sublime header in the 44th minute for the win over four-time champion Italy, which prompted La Republica to describe "hearts in hands, tears springing from deep and pride at its finest." As Pinto said in the BBC report, "The braver the bull, the better the bullfight." I'm just warning that when you add all that appeal to staggeringly beautiful bird beaks, you need to go gingerly and avoid tromping into arrogance.

For an example of how to do it, Costa Rica can always follow its CONCACAF brethren to the distant north.

Thank goodness we're so damned great.