''Copacabana belongs to Argentina,'' shouted Roberto Pons, rubbing his eyes clear of pepper spray as his long, gray hair flowed down his bare back to his Speedo swimsuit.

The 42-year-old air conditioning repairman was one of about 2,000 rambunctious Argentines who amassed Saturday on Rio de Janeiro's iconic beach to declare the superiority of their team - even before it had taken the field.

An estimated 50,000 Argentines are believed to have descended on Rio ahead of Argentina's match against Bosnia-Herzegovina on Sunday. Many Brazilians disdainfully speak of an Argentine ''invasion'' in this most Brazilian of Brazil's cities.

Fueled by social media, the impromptu street party Saturday was for the most part a fun-loving affair reflecting Argentina's high hopes for winning its first championship in nearly three decades. Fans dressed in the blue and white colors of the nation's flag hopped in place to a steady drumbeat, taunting any English supporter who happened to walk by with an in-your-face stadium chant: ''The one not jumping is a Brit!''

Another die-hard fan wearing a white robe, peaked cap and mask resembling Pope Francis, who is from Buenos Aires, walked around barefoot blessing anyone who crossed his path.

As the crowd swelled, a group of vastly outnumbered riot police deployed pepper spray to keep them from blocking traffic on the six-lane Avenida Atlantica running along Copacabana Beach.

''You're acting like little children,'' barked one cop, night stick drawn.

Argentina fans are among soccer's rowdiest, prone to violence often fueled by political grudges. One of its greatest foes is England, to whom it lost a war in 1982 for control of the Falkland Islands but scored a sweet revenge on the pitch four years later with Diego Maradona's memorable ''Hand of God'' goal in a key quarterfinal match.

Relations on field and off with neighboring Brazil also are full of friction. The two even fight over who has won the most head-to-head matchups over a century of competition, with each side claiming a one or two-win advantage based on what counts as ''official.''

But whereas Brazilians take in their stride their country's dominance of the sport and status as the world's seventh-biggest economy, much-smaller and economically unstable Argentina loves to boast about its two World Cup trophies - three less than Brazil - and reputation for producing some of the game's most-talented stars, including Lionel Messi, four-time FIFA player of the year.

''They hate us because we're the best,'' said Sergio Bonazza, a 51-year-old lawyer who traveled from Santa Fe, in Argentina's farm belt, in a 1998 Mercedes Benz bus that he and friends spent six months and more than $40,000 transforming into a 10-man camper.

In contrast, most Brazilians relish laughing at whom they frequently view as upstart, arrogant neighbors.

An ad running on television during the World Cup for classifieds website BomNegocio.com features a talking Diego Maradona couch whose owners have no choice but to vaporize in order to quiet its annoying ''Argentina, Argentina, Argentina'' chant.

Renata Parente, a 26-year-old medical student, also couldn't resist poking fun at the neighborhood intruders on Saturday. Walking back from the beach in a bikini, she cozied up to a group of four Argentine men dressed head to toe in blue and white. As a friend prepared to snap a photo, she flashed a big thumbs down.

''I'm going to post it on Facebook,'' she smiled while quickly slipping away amid the loud protests of the jilted Argentines. ''That's pretty ballsy to come to Brazil bearing the Argentina flag. They know no shame!''