It's the most popular sports event in the world. Soccer's World Cup finals, held every four years, will take place in 12 Italian cities, beginning Friday in Milan when defending champion Argentina meets Cameroon. It will end one month later with the championship game in Rome. Two teams from South America and three from Europe are favored among the 24-team field, which includes the United States for the first time since 1950.

A worldwide television audience of 26 billion -- up from 13.5 billion in 1986 -- is expected to watch. About 1 billion saw the 1986 title match, a figure certain to be surpassed July 8.

The favorites include Argentina, led by Diego Maradona, who was spectacular in the 1986 World Cup, and the Netherlands, which features scoring sensation Marco Van Basten, successor to Dutch hero Johan Cruyff; attacking midfielder Ruud Gullit, and Frank Rijkaard, a defender who can score.

Italy and Brazil, each of which has won three World Cups, and West Germany are the other favorites. Uruguay is a dark horse. England will try to duplicate its form of 1966, the only time it won. It would be a major surprise if the United States advanced beyond its three games in the first round, after which the field is trimmed to 16 and single-elimination play begins.

Two potentially volatile elements, the English and Dutch fans, come together June 16 for the England-Netherlands first-round game that has been placed in Cagliari, on the island of Sardinia, for security reasons. Uniformed police and plainclothesmen will number about 3,200 in an effort to control "hooligans."

The United States will open June 10 in Florence against Czechoslovakia, will play Italy in Rome June 14 and will conclude opening-round play against Austria June 19 in Florence. A 30-yard goal by midfielder Paul Caligiuri Nov. 19 in Port of Spain, Trinidad, gave the United States a 1-0 victory over Trinidad and Tobago to earn the trip to Italy. Generating enough offense is seen as the Americans' major problem.

Tony Meola, formerly of the University of Virginia, probably will be in goal for the Americans. Tall (6 feet 1) and quick, he hopes to play in Europe after the World Cup. "We don't worry about the odds," Meola said. "Whatever they are -- 1,500-to-1 -- we don't worry about it. That's the beauty of this team."

Other Washington-area players on the squad are Bruce Murray, a forward from Germantown, Churchill High and Clemson; Desmond Armstrong, Washington-born defender from Howard High School in Ellicott City, Md., and the University of Maryland; John Stollmeyer, midfielder from Jefferson High School and Indiana University, and John Harkes, former Virginia all-America midfielder. All are likely to start.

U.S. Coach Bob Gansler has called his team "anxious" and "ambitious." The players appeared ready during a recent East Coast exhibition tour. "We're tired of hearing all the negative stuff about us {in the media}," Stollmeyer said. "This team has achieved a lot and we haven't received the respect we deserve. Everyone says we're going to get killed over there, but we're going to surprise some people. I guarantee that."

The top two finishers in each of the six first-round groups and the four third-place finishers with the best records will advance to the second round. It could take three points -- a victory and a tie, for example -- for the United States to advance.

"It's a great achievement just to get there," Carlos Bilardo, Argentina's coach, said. "The important thing is that they {the United States} will be there and get the experience for the next World Cup." The 1994 championships will be held in the United States for the first time.

Bilardo is more concerned about Brazil. Its coach, Sebastiao Lazaroni, has made a revolutionary change in Brazil's style of play. Traditionally flashy on offense, Brazil now emphasizes defense. Last year, Brazil won the South American championship with victories over Argentina and Uruguay. In exhibitions, it has defeated Italy and the Netherlands. In its last 15 games, Brazil has given up only two goals. Maradona has called Brazil's Antonio Careca (the two are Napoli teammates) the best player in the world.

Other potential tournament stars include Uruguay's Ruben Sosa, England's Gary Lineker, Yugoslavia's Dragan Stojkovic, the Soviet Union's Oleg Protasov, Spain's Emilio Butragueno, West Germany's Lothar Matthaeus and Italy's Franco Baresi.

In Italy, expectations are high for the home team. The pressure on the players has been intense. Italy's manager, Azeglio Vicini, made headlines recently when he banned sex for his players until after the touranment.

Italy will be trying to use the 14th World Cup to showcase the country. "The World Cup is an opportunity to transmit, every day and to the whole world, an image of how much artistic and cultural richness our country possesses," said Paolo Arbarello, director of tourism for the Lazio region that surrounds Rome.

Security has been stepped up in all 12 Cup cities. Police will be on alert to avoid outbreaks by "fans" in streets, bars and stadiums. Authorities have focused on Cagliari and the England-Netherlands match. Earlier, Italy sent police officers to England to observe problems at stadiums there, and English police have traveled to Sardinia to advise the Italians on what to expect. English and Dutch authorities have met with Italian officials to offer advice on how to deal with potential troublemakers.

The Italian news weekly Panorama recently published what it called a manual for surviving the World Cup, a nine-page article entitled "Flee the World Cup," suggesting ways to avoid the month-long games, hoopla and traffic jams. But many Italian soccer fans are said to be enthusiastic about Italy's chances because the field is balanced.

With no team expected to dominate, most of the early attention will be focused on Argentina's Maradona and the Netherlands' Van Basten. "Maradona and Van Basten are almost unstoppable players," said Vicini, "and can make the difference between their teams and the others."