At the day's outset, it was a magical, magnificent celebration: a melange of giant floats, confetti, colorful costumes, music and dancing, plus the unmatched anticipation of another World Cup soccer spectacle.

But by day's end, the 110,000 spectators at sold-out Azteca Stadium were a restless group, having endured an often listless 1-1 tie between defending champion Italy and Bulgaria in the opening game of the 13th tournament.

For Bulgaria, it was a day of survival, with a late goal by Nasko Sirakov forging the deadlock. For Italy, it was a day of disappointment, watching its second-half dominance go for naught. And for most of Mexico, it was a day of waiting, impatiently anticipating the debut of its team Tuesday against Belgium, at the same site.

Italy, which played three straight ties in the preliminary phase of the 1982 World Cup to advance to the second round, had victory within its grasp today. Alessandro Altobelli scored in the 43rd minute of the first half and, with Bulgaria's methodical, plodding attack unable to generate much of anything after intermission, it appeared this Group A game would end at 1-0.

With 11 minutes remaining, forward Stoytcho Mladenov had to leave the match with a right-shin injury, leaving Bulgaria one man short. When Mladenov reentered, limping, with seven minutes left, Bulgaria seemed beaten.

But the underdogs created their only scoring opportunity of the half with 5:10 to go and capitalized on it. Kostadin Kostadinov, who entered as a substitute for Bojidar Iskrenov midway through the second half, crossed the ball from the right corner to Sirakov, who, between two defenders, headed it to the left of goalkeeper Giovanni Galli, who made a futile dive at the ball.

Sirakov, who had failed on a first-half scoring chance, shot his fist into the air, hopped over the advertising billboards lining the field and ran a victory sprint toward midfield.

When the match ended minutes later, the Bulgarians celebrated with arms uplifted. The Italians walked off the field with an air of resignation.

"[The late goal] causes some bitterness," said Italian Coach Enzo Bearzot. "We had a lot of chances to score in the second half. Our superiority emerged but, unfortunately, it was not enough."

"We do not fear anyone," said Bulgarian Coach Ivan Vutzov. "It was not an outstanding game, but that's due to the pressure that always occurs at the opening match. I feel we played well."

Still, for most of the second half, Bulgaria was badly outplayed. Italy's Gaetano Scirea, Pietro Vierchowod, Fernando de Napoli and Altobelli each had shots on goal, and Altobelli created several other chances. Italy, which often sits back passively once it gains a lead, stayed on the attack. But the finishing touch was not there.

"I think we need more vigor, especially on the wings," Bearzot said. "And I was not happy with [halfback] Bruno Conti, which is why he was removed."

Perhaps most shocking as Italy began its Cup defense was the absence of 1982 Cup star Paolo Rossi. Friday, Bearzot initially included Rossi on his 16-man roster, then reversed himself hours later and kept the center forward ineligible. (Each team has 22 players, of which 16 can be eligible for any one game.) Rossi scored six goals in the 1982 Cup, but has played poorly since.

Rossi's presence might have enlivened play in the first half. Bulgaria played its possession game and Italy waited to spring its renowned counterattack. Both teams seemed to be in the mood to accept a standoff rather than risk a first-day defeat.

The fans took alternately to whistling derisively, clapping rhythmically and chanting, "Mexico, Mexico." They even started The Wave several times.

Altobelli missed one good scoring chance and set up Antonio di Gennaro on another. Bulgaria's best chance came when star forward Plamen Getov passed to a wide-open Sirakov in the penalty area, but Sirakov whiffed on a header attempt.

De Napoli, a fullback, played brilliantly in constantly thwarting Bulgaria's advances, and Altobelli finally scored with less than two minutes left in the half on a right-footed kick from eight yards out after a crossing pass from di Gennaro.

Despite the large crowd, there were only 65 requests for medical attention. However, one fan had a stroke due to the "anxiety he felt after losing his ticket for the match just outside the stadium," according to Dr. Carlos Alberto Santiago, who said the fan was recuperating at Xoco Hospital.

As promised by the organizers, security for the opener was exceptionally tight. Police and soldiers armed with semi-automatic rifles lined streets near the stadium and thousands of troops and police stood guard in and around the facility as a military helicopter hovered overhead.

As fans filed into the stadium, police searched bags for weapons or other banned objects. Journalists entered through a special gate, then had to walk through a metal detector.

Throughout the city, people who could not afford or get tickets gathered in plazas to watch the game on giant TV screens.

Brazil, the 3-to-1 tournament favorite, according to London bookmakers, is also the team of choice among experts polled by local newspapers. The long shots are Iraq and South Korea (at 500 to 1) and Canada (1,000 to 1).