An Argentine tenor, who has sung at the Met and La Scala, made a triumphant debut last week at the Teatro Colon, Buenos Aires' magnificent opera house. From the sixth balcony--el paraiso (paradise), as they call it--where standing room sells for 50 cents a ticket, the bravos descended in waves.

Five minutes. Ten minutes. The shouts and whistles echoed across the gilded cupola and through the chandeliers as Luis Lima, who was playing Tosca's Cavaradossi, stood frozen in a dramatic pose. Down in the orchestra, where the red velvet seats with brass fittings cost $25 a night, the patrons in silk and sequins lost patience, clucking and shushing and gesturing impatiently toward the rafters.

Paradise would have none of it.

The class warfare, fueled by patriotic emotions, was a curious sideshow in an evening that began with the thunderous strains of 3,000 voices singing the Argentine national anthem. But in the end, even the aristocrats tossed roses to Lima and a few women cried for love of art and country.

In this capital of 9 million, the war over the Falkland Islands seems distant. Yet, in small ways, it touches every aspect of Argentine life.

No one would stop going to the opera in a country where more than 40 percent of the population is of Italian extraction. But at the bus stops outside the Colon, where the patrons of paradise wait in orderly lines after the performance, every other lapel is decorated with a fraying strand of blue and white ribbon, the national colors.

A POPULAR RESTAURANT on the Avenida Reconquista, the London Grill, didn't go out of business. It merely renamed itself The Grill and removed Queen Elizabeth's portrait from the entrance. The Franco-Inglesa pharmacy, one of the oldest in the city, is now the Franco pharmacy. The movie "Chariots of Fire," a moving tribute to two British athletes, was banned after a successful five-week run. But on television, one can freely watch American television shows, dubbed in Spanish.

Across town from the Colon, business at the 22,000-seat Luna Park boxing arena has never been better. On a sweltering, Indian summer evening, the Cafe Ringside, with its framed snapshots of Argentina's greats, is filled with fans sipping rich black coffee with hot milk. The lines at the box office for $2 tickets wind around the block. Inside, Ubaldo (Uby) Sacco and Roberto (The Turk) Alfaro are vying for the South American light welterweight championship. Argentina has 98 professional boxing arenas but Luna Park, which boasts that Mohammad Ali has fought here and Frank Sinatra sung here, features the stars.

"Four world titles were decided here last year," boasts Daniel Van der Beken, the arena's press agent. Yes, he tells a questioner, he does think about the war down south. "But you can't stop the country for that," he says. "People want to be distracted. We can't let our inner calm slip away."

A week ago, proceeds from the Saturday night fight went to the Patriotic Fund, a multimillion dollar, government-sponsored project to raise money for the war. But this week, the only reminder of the conflict was a sports promoter who, passing through a throng of radio reporters, did a hilarious takeoff of Foreign Minister Nicanor Costa-Mendez' daily routine: "No senor, No comments today," accompanied by exasperated gestures that have become familiar to thousands of television viewers during the last six weeks of negotiations.

The ringside seats are filled with men with broken noses, former champs dressed in shiny suits, with blue and white ribbons in their lapels. "Coca-Cola and smiles for you," says an immense neon sign in Spanish on the wall, but the fighters below do not look happy.

For 11 rounds, Ubi and the Turk have danced and snorted, jabbing and hooking, while the crowd oohed and aahed over the one-two combinations. Now, in the 12th and last round, Alfaro is cut over the right eye and the blood trickles down his face.

It was a good fight, a close fight, between two Argentines. The bell rings. The judges pronounce Sacco the winner. He grabs the Alfaro by the knees in an affectionate bear hug and whirls him in the air as the crowd roars.

ARGENTINA'S MOST FAMOUS world champion, the late Luis Angel Firpo, known in the United States as "the wild bull of the Pampas," has been featured on Argentine television of late in an old film clip where he pitches Jack Dempsey out of the ring. This spot is part of a propaganda campaign, designed to show what Argentina is about to do to Britain.

Firpo is buried in La Recoleta, Buenos Aires' opulent cemetery where presidents in polished cedar caskets with silver handles lie in chapels with stained glass windows.

Many of the mausoleums have impressive statues of their occupants, including one of a young girl who, it is said, was buried alive after a heart attack and awoke to stagger across the street before expiring. Firpo's grave is notable for a larger-than-life bronze figure of the champ, dressed in his boxing robe, opened to show his massive chest.

Now the cemetery is full, explains a guide, and the new Argentine heroes, who have died for "the Fatherland" will have to be buried elsewhere.