For Enzo Bearzot, there is no in-between. He is the coach of Italy's World Cup soccer team, and when he returns home, he will be the most revered man in his country or the most reviled.

The 13th World Cup -- the tournament is played every four years -- opens Saturday at sold-out, 110,000-seat Azteca Stadium with defending-champion Italy playing Bulgaria.

Italy -- along with Brazil the only three-time winner of soccer's most prestigious event, wants to avoid a misstep against the rugged, defensive-minded Bulgarians. "The first match is all-important," Bearzot said.

For many Italians, every Cup match is a matter of national pride. On Saturday, easily more than half of Italy's population of 57 million is expected to watch the match on TV.

Bearzot, 58, knows those people will judge him and his players harshly if the team continues its recent erratic play.

"Some say that [soccer] is religion here," Bearzot said. "All I know is that it defines a lot of people's lives. . . . If we do not win the Cup , the reaction may not be too bad if we make a good, respectable showing. But if we embarrass ourselves, then that is a different story."

The story today involved Italy's 29-year-old star, Paolo Rossi, who was removed from the starting lineup by Bearzot. Against Bulgaria, Alessandro Altobelli, Guiseppe Galderisi and Salvatore Bagni will start on the forward line.

Rossi, who scored six goals during the 1982 Cup, has floundered since. Many critics have insisted Bearzot replace Rossi, but in the team's practices in Puebla, 80 miles southeast of here, the center forward had shown flashes of his renowned moves and creativity. Still, Bearzot said today, Rossi had conceded he was not at his best.

"I think I am in Mr. Bearzot's plans to play a lot against Bulgaria," Rossi said. "It would be a blow not to play in this game, and I think I have played sufficiently to show my merits."

When Bearzot referred to a "different story," he was undoubtedly thinking of the 1966 Cup, when North Korea shocked Italy, 1-0 -- a defeat perhaps unequaled in Italian soccer history for sheer humiliation and embarrassment. The Italian team flew home in early morning to avoid the public, but many fans were at the airport. They threw vegetables at the players.

Four years ago in Spain, as Bearzot's team advanced to the title match against West Germany, Italy reached a fever pitch, and the Cup triumph set off a raucous, all-night celebration throughout much of the country. Bearzot and his players returned to public adulation.

The Italian team's chances of winning a second straight Cup seem marginal, at best. In addition to the team's inconsistent play of late, there is the fact that no European nation has won the World Cup when it has been played in Latin America. Also, only two nations have won consecutive Cups (Italy in 1934-38 and Brazil in 1958-62).

Since its 1982 success, Italy has looked listless in exhibition matches and shockingly won only one of eight matches in the preliminaries to the 1984 European Nations Cup finals. And it did not have to labor to gain a spot among the World Cup finalists this year since, as the defending champion, it was awarded an automatic berth.

"We have not had a good competitive edge," Bearzot said.

The Italy-Bulgaria match will begin the preliminary phase of the month-long tournament. There are six groups of four teams each. After round-robin play is completed within each group, the top two teams from each group and the top four third-place finishers will advance to the round of 16, at which point the Cup becomes a single-elimination tournament. Two points will be awarded for a victory and one point for a tie in the preliminary phase, with goal differential being the primary tie-breaking procedure in the group standings.