ROME, JUNE 25 -- Potentially, there hasn't been a time like this in Italy since 1934, when the country hosted the World Cup and won it at the same time. It explains, in part, the state of high, intertwined emotions here. The Italians, in a sense, want it all: They want to be fine hosts, hurting no one's feelings, but they also want the world to know what they consider the true home of soccer in 1990.

They worry. They worry if it's possible to send everyone home a happy loser. They worry about a lurking West Germany. Today they worried about tonight's match with Uruguay, which started the evening as one of only three countries to hold an advantage over Italy through the years. By evening's end, Italy had evened the ledger and eliminated Uruguay from the World Cup, 2-0, advancing to the quarterfinals.

Italian fans stopped worrying long enough to celebrate for hours into the morning.

Their national team, known as the Azzuri, the Blues, took another step toward a repeat of '34, winning the Cup (which they also did elsewhere in '38 and '82) in Italy.

Yet their quarterfinal matchup here at Olympic Stadium Saturday night will be against an unexpected opponent, stubborn Ireland, which advanced today in Genoa with an emotion-packed upset of Romania, 1-0 (5-4 on penalty kicks), the fifth and decisive one taken, after a scoreless deadlock carried through extra time, by David O'Leary, London-born but Dublin's own.

Ireland, which had never before made the 24-team Cup finals, would seem to face an impossible assignment playing Italy, which has 22 immensely talented players to choose from. The Irish have managed only two goals in four games, advancing on three first-round ties and today's shootout after the scoreless draw. Objective observers here believe Italy will cut through Ireland like butter.

Ireland's coach, tall Jack Charlton, was asked, tongue in cheek, today in Genoa if he thought his team would take Rome by storm. First, the coach thanked his "lad" O'Leary, who happens to be 31 years old. Then, taking a long puff on a Red Auerbach-style victory cigar, Charlton replied unhesitatingly, "We will be better in the evening in Rome than the heat of the day here today."

It sounded like just enough to make Italian fans worry some more. They worried during the first half tonight, and into the second. Uruguay held its own; it's a country that's been two-time World Cup champion and winner of the America Cup tournament a record 13 times.

But in the 52nd minute, Italy's Anzeglio Vicini made a brilliant coaching decision. Utilizing his bench strength, he inserted forward Aldo Serena, who would be the tallest man on the field. Three minutes later, Uruguay substituted in dynamic Ruben Sosa, an ace withheld until Oscar Tabarez, Uruguay's coach, thought Sosa would run wild on fresh legs. At 5 feet 6, Sosa would be the shortest on the field.

Italy's Vicini had picked the tall straw. Immediately, Serena, an Inter Milan club star celebrating his 30th birthday, began using his height to control balls with his head. Vicini had shuffled his cards, changing the game's tactics.

Serena set off a number of crossing passes to the people's choice, Salavatore Schillaci, a small darter. In the 65th minute, Serena took a pass from Roberto Baggio and flicked the ball between the legs of Uruguay defender Nelson Gutierrez to Schillaci, who scored easily with a left-footer -- as he said later, a "full foot" shot for his third goal in four Cup games, the first two of which he got in as merely a substitute. "The most satisfying goal is a header," said Schillaci, 25, born and raised in Palermo and now freed from the obscurity of Sicilian sandlots. "But the one tonight was the one I tasted the most."

Serena's birthday party continued. In the 83rd minute, Uruguay's Jose Perdomo fouled Pietro Vierchowod. Giuseppe Giannini took the free kick, floating it high toward the front of Uruguay's goal where the tall Serena leaped, rotating his head more than Uruguay's goalie, Fernando Alvez, anticipated. The ball went into the net to Alvez's right as he was moving left.

Almost all of the 73,303 in humid Olympic Stadium went wild with ecstasy. As Italian keeper Walter Zenga completed his shutout, thousands of the green, white and red Italian flags were waved in unison, and chanting turned to song.

Vicini, under questioning but giving away as little as possible, concurred in a sense that he had, perhaps, the most remarkable number of quality reserves ever assembled, and that, indeed, he had switched tactics sharply by substituting in Serena. Vicini went this far: "I can count on players of different characteristics."

He called the victory "another small but important step toward our ambitions, our dreams."

And in a way, he foretold how difficult it would be for Ireland here Saturday night. "Playing on the home pitch," he said, "we are almost always on the attack."

It's a team and a crowd extremely difficult for any opponent to contend with. The rooting force behind the Blues is like armed forces' divisions united into a single corps. Regional rivalries centered around club teams, such as Napoli in the south and Juventus in the north, which compete in the Italian League, are set aside in a solid front of nationalistic support.

Late in the game, Uruguay, which has been known to play rough, began dumping Schillaci as if he were the fabled Diego Maradona. Vicini said that with experience, Schillaci and Baggio would "suffer less of these rough tactics, but they're quite evident. But their game, like Diego's, is real miracles -- and rough tackles."