On Tuesday, about 41,500 fans packed the standing-room areas of the tiny Sarria Stadium here to watch Italy and Argentina play in their second-round World Cup soccer game.

Never mind the 200 unsold seats in the high-priced stands; that's another story. What matters is that many times that number were stranded outside, unable to get standing-room tickets, although some could be found.

Judging from the 15,000 or so Italian fans at the game, many of whom just drove over for a few days, it would have been pretty easy to sell out the cavernous Nou Camp stadium, which is about a 10-minute walk away across the great Avenida de Ladiagonal.

The day before the Argentina-Italy game, about 5,000 fewer fans were scattered throughout that 105,000-seat stadium--said to be Europe's largest--to watch Poland play Belgium.

Poland and Belgium are interesting teams and played an entertaining game. But these two teams just do not draw well outside of Warsaw and Brussels. So why weren't the stadiums switched for the games or both games played at Nou Camp, since there was nothing going on there, anyway?

Welcome to the world of FIFA and international soccer politics. FIFA, known universally by its French acronym, is the International Federation of Association Football and has 140 member nations.

Belgium, backed by the Soviet Union, which is in the same second-round group, refused to go along with FIFA President Joao Havelange's plan to switch the stadiums the two Barcelona groups were playing in.

Havelange reasoned, logically, that games involving the group made up of Italy, Brazil (Havelange's native country) and Argentina would sell many more tickets than that with the Poles, Belgians and Soviets. Besides the fact that tens of thousands of Italians and Brazilians are here for the Cup, Argentina's young superstar, Diego Maradona, will be playing for FC Barcelona next fall, and there is more than passing local interest in his performances.

These second-round groups were prearranged and concocted by men who reasoned that Argentina would win its first-round group and end up in the Nou Camp group for the second round.

They also reasoned that Italy would win its group and provide a fairly strong second draw in the Nou Camp section. The Belgians and the Poles spoiled that by finishing ahead of the favorites, and the Belgians, already angered that England was selected as one of the six pretournament seeds ahead of them, fought back, sending their national soccer association chairman to FIFA headquarters in Geneva to argue the point.

"If you look at it from a sporting point of view, you have to admit that Belgium had a right to be upset," pointed out Belgian journalist Francois Colijn, who is not known as a yes-man for his country. "On a sporting basis, you have to remember that Belgium was a finalist in the last European championships and then, after all, they beat Argentina here and played to win their group precisely so they could have their games in prime time at the Nou Camp Stadium."

However, Colijn noted, the British have a special role within FIFA, and so "someone came up with this propaganda stunt--why not make the five former world champions and the host country the six seeds?"

That idea went over big with the Spanish tournament organizers. As for Britain's special FIFA role, it is interesting on another level, and explains why the British have four separate FIFA members: England, Scotland, Northern Ireland and Wales--and all but Wales qualified for this year's World Cup.

FIFA is historically very sensitive about Britain's role, since in the 1920s, '30s and '40s Britain withdrew from the world body twice for a total of 24 years for political reasons and England didn't even bother to join FIFA until 1905, when the international group was well into its second year.

The three other British countries waited until 1910. What gives the British their power within FIFA today is the continued strength of the autonomous but closely related International Football Association Board, which has four members each from each of the four British FIFA "countries" and four from the rest of the world.

Even for those years when Britain was out of FIFA, one form or another of this arrangement continued. The board is important because it controls the rules of the game, organizes and runs international tournaments and regulates the movement of players between countries.

So the Belgians didn't have a prayer of being seeded ahead of England for the World Cup, despite their better performance as a national team in recent years, and they weren't about to be inconvenienced by a last-minute stadium switch.

Fortunately for them, the Soviets were just as stubborn about not switching, which brings up another interesting aspect of FIFA politics.

Much like the International Olympic Committee and the United Nations--both of which, incidentally, have fewer members--FIFA is increasingly dominated by a Third World and Soviet Bloc majority.

While the international board makes decisions on rules and tournaments, the entire membership votes on things such as how many teams will be in the World Cup, where it will take place, and so on.

In recent years, there has been much evidence of the increasing politicization of world soccer. Currently, South Africa is out of FIFA for political reasons and Chad is out because it cannot pay its dues. Taiwan, after years of membership, is out and China is in after a move that was tied with another power play that saw Israel expelled from the FIFA-associated Asian Football Confederation.

Since then, Israel has been shopping around for another regional confederation to join, but so far it has been unsuccessful. The Europeans turned the Israelis down, citing logistical problems, but did let Israel--which is still a member of FIFA--participate in a European qualifying group for the World Cup.

There are other ways in which politics affect the World Cup scene. Josef Huber of Vienna's Kurier newspaper described four instances where penalty kicks were either called or denied in questionable circumstances: "The referee carried hometown Spain into the second round," said Huber, "and kept two penalties from the Soviet Union so Brazil wouldn't stumble in its first game."

Jock Stein, the coach of Scotland's eliminated team, wondered about refereeing assignments even before the tournament started, worrying that the American referee assigned his first game with New Zealand might be short of international experience, then questioning how neutral one could expect a Latin referee to be in Scotland's match with Brazil and an East European referee in its encounter with the Soviet Union.

Since refereeing assignments are by nature so political, you might expect that the FIFA officials who make these assignments might study their history and political science a bit more closely.

Surely the Austrians were surprised when, for their second-round match with France, the referee was Hungarian and the two linesmen were a Czechoslovak and a Yugoslav--all three officials from countries that not all that long ago were part of the Austro-Hungarian empire.

It would have been simple enough to assign Latin Americans or Third World officials, but who is to say what considerations went into choosing that group?

Finally, FIFA is important as the final arbiter of any disputes that arise here, and one of the most heated ones so far concerns the scandalous performance of passive soccer the West Germans and Austrians put on during their first-round encounter.

The Germans won, 1-0, ensuring both teams a place in the second round ahead of the popular Algerian team that defeated West Germany and Chile. The Algerians lodged a protest, demanding that both teams be fined and that Algeria be moved into the second round.

A fine, at least, would have seemed acceptable, but neither team received so much as a slap on the wrist. It should be noted that the West Germans, represented by FIFA vice president and tournament organizer Hermann Neubergen, are also a power inside FIFA.