Mexico continued its magical home-field ride through this 13th World Cup, getting goals from Manuel Negrete and Raul Servin today to oust Bulgaria, 2-0, and advance into the quarterfinals.

Once again, Mexican shortcomings were lost amid 114,508 frenzied fans and another weak opponent, allowing the home team to advance as far as it ever has in World Cup play. Mexico, which will play the winner of Tuesday's West Germany-Morocco match, made the quarterfinals only one other time, in 1970, when the Cup also was held here.

Later tonight, the government news agency Notimex reported one person killed and another wounded during celebrations on city streets but it was unclear if the shooting incident was more attributable to a traffic accident or to the soccer victory.

In today's other game, in Leon, Belgium reached the quarterfinals by upsetting the Soviet Union, 4-3, on overtime goals by Stephane Demol and Nico Claesen.

The turning point of the Mexico-Bulgaria match might well have occurred the moment when they let the gates open three hours beforehand to let the crowd in. Somewhere in Azteca Stadium, there might have been Bulgarian fans, but they probably wore Mexican garb in the interests of world peace. Azteca is a double-decked, enclosed stadium, meaning that the deafening cheers usually echo through the premises rather than drift out into the smog.

Mexico's good soccer fortune remained intact today. Its opponents thus far -- Belgium, Paraguay, Iraq and Bulgaria -- are not among the elite teams. For all the certainty of fans here concerning Mexico's Cup bid, Coach Bora Milutinovic's Mexican team looks quite ordinary and probably would lose to eight or 10 of the nations still in the tournament.

"There are some serious problems with our defense," he said. "I saw that today. But I'd like to concentrate on the positive. Keep in mind that our second goal, which put our minds at ease, was scored by a defender."

"Of course," Bulgarian Coach Ivan Vutsov said, "the spectators add to Mexico's performance, but that's not the only element counting toward their success. However, they will have to upgrade their performance in future matches. As for Bulgaria, we did not perform well today, but realistically, we could not hope to go any further than today."

The Bulgarians, who have yet to win in 16 World Cup matches covering five Cup appearances, were plodding and sluggish. Their best player, Plamen Getov, was benched early in the second half because of poor performance. They turned several fast breaks into broken plays with their immobility and slow-motion reflexes.

If not for goaltender Borislav Mihailov, Bulgaria would have trailed by two or three goals early. But Mexico's star striker, Hugo Sanchez, who sat out the last match because of two yellow cards, was denied twice by Mihailov on good scoring chances.

Finally, in the 34th minute of the first half, Mexico scored on some nifty volleying passes between Negrete and Javier Aguirre. Just inside the penalty area directly in front of the goal, Negrete volleyed to Aguirre, who passed it right back. Negrete, from 15 yards out, used a twisting, acrobatic left-leg kick to score into the right corner of the net.

"It was a move I don't do often," Negrete said. "The ball was centered toward me, and I saw the possibility of doing a scissors trick. My first intention was to play the ball much higher into the net."

The goal seemed inevitable because Bulgaria's defense allowed Mexico to control the ball around the penalty area without much resistance most of the time.

In the second half, Bulgaria continued to misplay scoring chances, but most of the time, it did not even try to set up legitimate attacks. The Bulgarians' offensive philosophy seemed to be: shoot wildly from 30 or 40 yards out, watch the ball go over the goal line and retreat. They retreated well.

In the 16th minute of the second half, Mexico got its insurance goal quite simply. Negrete had a corner kick, and Servin headed it home from very close in.

After that, Bulgaria showed its only life of the match. Atanas Pashev, Petar Petrov and Anyo Sadkov all had good shots, but Mexico's Pablo Larios -- an often frenetic, inconsistent performer -- made fine saves.

Sanchez, Mexico's temperamental, moody superstar, was barely heard from in the second half after creating many scoring chances earlier.

As the second half neared its end, the crowd rose. The fans grew louder and waved their flags madly. Another unabated, night-long Mexican celebration was beginning, and with it would come greater expectations than ever.

"Let's be realistic," Milutinovic said. "You can always dream. We have played with the idea of being Cup winners. But I have a great deal of respect for West German football and for the Moroccans. But as I always say: the game lasts 90 minutes and we can beat anyone. I am very optimistic."

The Belgians, who finished third in Group B, twice came from behind in regulation to tie the score against the Soviets. In the first of two 15-minute extra periods, Demol crept behind the defense and headed in a long pass by Eric Gerets at 13 minutes.

The tiring Soviets allowed another goal three minutes into the second extra session when Claesen volleyed a right-foot kick home from 20 yards.

The Soviets, winners of Group C, got one goal back when Igor Belanov scored on a penalty kick, his third goal of the game and fourth of the tournament. But, with little energy left, the Soviets were eliminated.

FIFA, the governing body of the sport, fined the Spanish soccer federation $12,000 for giving one of its players an unidentified improper medicine. Sources said that player was Ramon Caldere, who scored two goals against Algeria on Thursday.

FIFA also rejected Uruguay's appeal of its $12,000 fine for rough play and improper conduct, and upheld the suspension of Coach Omar Borras for Monday's game against Argentina.

A confrontation of two of the world's best goalkeepers, England's Peter Shilton and Paraguay's Roberto Fernandez, was jeopardized when Shilton wrenched his right knee in practice. The teams will play a second-round match Wednesday at Azteca Stadium.