ROME, JUNE 22 -- Now it really gets serious.

Action in the World Cup finals' single-elimination second round of 16 will begin Saturday, with four days of matches promising some of the best soccer imaginable -- and doom for at least two of the greatest teams in the world.

By a quirk of pairings, two games of great import will take place Sunday in northern Italy. At 5 p.m. (11 a.m. EDT) in Turin, defending Cup champion Argentina, with charismatic star Diego Maradona, will face Brazil, which this year believes it can win the Cup. At 9 p.m. (3 p.m. EDT) in Milan, current European champion Netherlands will meet West Germany, the 1990 World Cup cofavorite with Italy.

It's rare for four of the Cup's top five teams to meet so early. The championship will not be decided until July 8 in Rome. But Italy couldn't be happier to sit back waiting for its match Monday in Rome against Uruguay and watch two serious threats eliminated. The team Italy fears most is West Germany, and so the team and its fans will be rooting hard for the Dutch.

Italy, Brazil, Argentina, Germany and Uruguay have won 12 of the 13 World Cups. The only other country to win was England in 1966. England will be playing in one of two other attractive second-round games: Cameroon-Colombia Saturday in Naples and England-Belgium Tuesday night in Bologna.

Cameroon's success has made people happy, and a "Lions of Africa" T-shirt a collector's item. Scoring major upsets of Argentina and Romania in the first round, Cameroon provided instant excitement.

At 5 p.m. Saturday (11 a.m. EDT), the spirited, French-speaking Cameroonians will have to solve one of the game's great eccentrics, Colombia's little but fearless goalkeeper, Rene Higuita. An extreme individualist, Higuita takes penalities, likes to double as a substitute fullback (although he's not expected to here) and has been known to range from the goal as far as midfield -- the equivalent of a shortstop fielding a ball against the center field fence.

The long-awaited answer as to where England and its troublesome fans would hit the mainland after being isolated on Sardinia in the first round has been answered -- but not to the liking of the lovely city of Bologna. An academic center, Bologna faces massive security efforts shifted over from the island.

With a 1-0 victory over Egypt Thursday night -- the only game played in its group that wasn't a tie -- the weary and injured English lucked into the maximum number of days of rest before playing a Round 2 game. However, it drew a tough opponent. Belgium is strong and fast and has been maturing as a team along with its prime force, midfielder Vicenzo Scifo, of Sicilian ancestry.

Two teams in the final 16 are real charmers. Ireland and Costa Rica have advanced in their first appearances in the World Cup finals. Costa Rica hadn't even made hotel reservations for round two.

Based during the first round on Sicily, the Irish play more tie games than any other national team. The tie is coach Jack Charlton's way of maximizing his talent. Ireland extended its unbeaten streak in international play to 16 Thursday night in remarkable fashion, coming back to draw with the flabbergasted Dutch just as they came back June 11 to tie England. For their heroics, the Irish won the right to play Romania Monday in Genoa.

The Costa Rican team has set off delirious celebrations in its small country that sits between Nicaragua and Panama. The Costa Ricans surprised Scotland, 1-0, starting the Scots' exit; lost by a goal to Brazil, and registered an unexpected 2-1 victory over Sweden Wednesday to qualify for the second round. At home, happy fans poured into the capital of San Jose. A holiday for all state employees was declared.

On the way to the World Cup, Costa Rica changed coaches several times until settling on Yugoslavian Bora Milutinovic, 48. He once played in Italy, and became coach of Mexico's national team in 1986. Remarkably, he took over the Costa Rican team only 90 days before the World Cup finals and transformed it.

He made a winning move against Sweden, sending in substitute Hernan Medford, who got the winning goal, eliminating Sweden. "This is an historic victory," Milutinovic said. Costa Rica's captain, Roger Flores, lauded the coach, saying: "We thank Bora for this victory."

Saturday in the southern city of Bari, Costa Rica will take on Czechoslovakia, which started the Americans' demise with a 5-1 lashing. The Czechoslovaks have plenty of muscle and play a midfield power game, with speed down the flanks.

Finally, Spain will play Yugoslavia Tuesday in Verona in what should be a tough game for both. The two started below par, with Yugoslavia getting crushed, 4-1, by West Germany and Spain just managing a 0-0 tie with an unimpressive Uruguay. But both Yugoslavia and Spain have improved a bit -- especially Spain as its key player, Gonzalez Michel, scored a hat trick against South Korea. Spain also boasts the dangerous but yet-to-strike Emilio Butragueno, known as "El Vuitre," or "The Vulture."

The Italians won't regard Uruguay lightly Monday night at Olympic Stadium. They're familiar with Uruguay's shifty, speedy little Ruben Sosa, who plays for the Lazio club team of Rome and is the most famous in his family of 14 from the outskirts of Montevideo.

West Germany has been awesome offensively and consistent in every aspect of play. It's led by one of the world's finest players, Lothar Matthaeus. On the Dutch side, Marco Van Basten barely has been visible in three games after being widely touted as perhaps the Maradona of the '90 Cup. But Ruud Gullit, after missing a year with an injury, showed Thursday night against Ireland why he is truly a magnificent all-field player.

Meanwhile, Sunday in Turin, a carnival atmosphere is expected for a classic South American matchup. The end for one of these teams, Brazil or Argentina, will be sad. Brazil has assembled its most promising team since 1970. It's shifted to a defensive emphasis, but has a lightning scorer at center forward, Antonio de Oliveira Filho, called Careca.

In the 1986 World Cup, Maradona, 5 feet 5, leaped high for a controversial score -- using what he later called "the hand of God" to score the first goal of Argentina's 2-1 quarterfinal victory over England. His second goal came four minutes later. So while many say God will not be on Maradona's side Sunday, English coach Bobby Robson's words might be remembered: "Maradona can win a game on his own in five minutes."