The U.S. national team is out of the World Cup, but you can still root for a team. Here are the remaining countries and why you should root for—or against—them. (Tom LeGro/The Washington Post)

While hordes of Argentine fans on Copacabana beach celebrated another World Cup victory by their national team Tuesday, Brazilian Gustavo Bog, 27, had draped the ripped remains of an Argentina team T-shirt over his shoulder — a souvenir of a scuffle that broke out just as the game finished.

Chanting between Brazilian and Argentine fans had gotten out of hand during the broadcast of the match at the FIFA Fan Fest held on the beach. “There was a punch. An Argentine shirt was ripped,” said Bog’s friend, Arturo Freitas, 24. The scuffle had ended with a handshake — but Bog held on to the ripped sky-blue-and-white shirt as a trophy.

Argentina vs. Brazil is one of the greatest ongoing battles in world soccer. The South American neighbors have played each other more than 100 times since first meeting in 1914, according to the author of a 2009 book on the series. Both fierce and friendly, it is like an intense sibling rivalry between high-achieving, alpha-male brothers who occasionally come to blows.

Now the rivals are two wins apiece from what would be their highest stakes matchup — in the World Cup final at Rio’s iconic Maracanã stadium on July 13. In the quarterfinals, Brazil will play Colombia on Friday in Fortaleza, while Argentina will go against Belgium on Saturday in Brasilia.

“To win the final with Brazil at the Maracanã is something like the ultimate dream for any Argentine fan,” Ezequiel Fernández Moores, one of Argentina’s best-known sportswriters, said in an e-mail interview. “It would trump all World Cups and be an eternal postcard image.”

The United States soccer team lost to Belgium, 2-1 on Tuesday, but goalie Tim Howard's record performance helped him to win the love of Internet users. (Kiratiana Freelon/The Washington Post)

At the Fan Fest, Rio native Diogo Barcelos, 59, said: “Our rivalry is just football. We consider the Argentines brothers,” He demonstrated his point by wearing a yellow Brazil team T-shirt and a furry hat in Argentina’s sky blue and white, wrapping his arm around the shoulders of his friend Luciano Cazenave, 55, from Buenos Aires.

“It is an old story with more flavor. It is a rivalry to play with more passion,” said Cazenave, wearing Argentina’s colors on his hat, T-shirt and painted on both cheeks.

As Cazenave and Barcelos talked, they were interrupted by Freitas, who took a more heated view. “It was healthy. But they are making a lot of mess. They are increasing the rivalry,” said Freitas, who accused Argentine fans of urinating on Rio’s famous beaches. “If there is a final between Brazil and Argentina, there will be a lot of fighting.”

In the past it has been much worse. In 1825, Brazil and an early incarnation of the Argentine state fought a three-year war over territory that later became Uruguay. The soccer rivalry began in 1914, with a 3-0 Argentina victory in a friendly. A week later, Brazil won, 1-0, to claim the first Copa Roca — a competition set up by the Argentine president of the same name to foster friendship.

As with many great rivalries, their styles are complementary. “The Argentines would love to play football as fancy as the Brazilians, and the Brazilians would love to play with the drive and will that the Argentines have,” Newton César de Oliveira Santos, author of the 2009 book “Brazil-Argentina: Stories of the World’s Greatest Football Rivalry,” said in a phone interview. “The rivalry exists, but it hides a big admiration that each has of the other.”

The South American siblings are evenly balanced. Brazil’s Pelé is widely regarded as the best player of all time; Argentina’s Diego Maradona runs a close second. Brazil has won five World Cups to Argentina’s two. Argentina’s brilliant attacker Lionel Messi has won FIFA’s player of the year four times. Neymar, Messi’s young teammate on professional powerhouse Barcelona, is the attacker Brazil is depending on to win the World Cup. Each has four goals so far this tournament, tied for second among all players.

Players from both countries respect each others’ strengths. “I like the way they play . . . the technique of Brazilian football,” said Ricardo Gareca, a former Argentine national team player who now is coach of the Sao Paulo club Palmeiras. His Brazilian forward José Henrique said of the Argentines, “They are players with a lot of guts. Also, they really like to enthrall.”

Santos’s book details some of the long duel’s most bitter moments: South American championship games in 1937 and 1946 marred by fights and fans running onto the field. Argentina won both games, 2-0. But Argentine defender Salomón had his leg broken in a tackle in the second game.

In the 1990 World Cup in Italy, a spectacular dribble by Claudio Caniggia left Brazil goalkeeper Taffarel on the ground as the Argentine attacker rounded him and scored to eliminate Brazil from the tournament. In the 2004 Copa America final, Argentina held a 2-1 lead before Adriano equalized in injury time for Brazil, which went on to win in penalty kicks.

Both teams raise their game when they play each other, said Romulo Frisch, 37, a native of Rio who said he counts Argentines among his close friends. In the end, he said, “It is just football.”

But football, in South America, is sometimes a matter of life and death: There were 30 soccer-related deaths in Brazil last year, and 2,435 Argentine football fans were banned from entering Brazil for the World Cup over fears of violence.

Tens of thousands more Argentine fans have come to Brazil — most enjoying the hospitality and close-fought soccer. “All the Argentines tell me they have been treated very well,” Cazenave said. “We are good friends.”

Not always. In Belo Horizonte on June 21, Brazilian and Argentine fans exchanged a hail of bottles and cans after Argentina’s dramatic 1-0 victory over Iran. The Web site UOL reported that Argentina fans broke seats at Sao Paulo’s stadium during Tuesday’s round-of-16 victory over Switzerland. The Folha de S. Paulo newspaper site reported police used a percussion grenade to clear Argentine fans off the streets of a bar district later that night.

On Tuesday, as a group played Brazilian samba music on stage at the Copacabana Fan Fest, Argentines commemorated victory. Clutching a beer, Aquiles Saldaño, 40, from Cordoba, Argentina, quoted from a comedy pop song popular with Argentine fans, in which “bitter” Brazilians are informed that Argentina’s Pope Francis, Messi and Maradona are judged greater than Pelé.

“Brazil is very beautiful. The people are nice,” he said. “But they robbed my license plate, and I can’t drive around.”

Brazilians have returned the jibes: On Wednesday, a shaky black and white video shot around Brazilians social media. In it, a small Argentine boy blows bubbles while discussing the World Cup, repeating that Brazil will win “because they are really good.”

“Between Brazil and Argentina there is rivalry in everything,” Maria Kalafattich, 32, from the Argentine city of Formosa, said at Tuesday’s Fan Fest.

“We will see Brazil and Argentina in the final, if God wishes,” said Brazilian Fernado da Silva, 38, who also attended the Fan Fest.

But if Argentina should win?

“It would be terrible.”