One of world football's great moments, Brazil vs. Argentina, descended into pure farce in Sao Paulo on Sunday when the game was suspended after just four minutes after officials from Brazil's health authority walked onto the field.

The incident proves that the big problem hovering over these rounds of World Cup qualification was not the conflict between Europe's clubs and South America's national teams. True, tension between them always exists.

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"The referee and the match official will take a report to the FIFA Disciplinary Committee and they will decide what steps to take," said a statement issued by CONMEBOL.

But the latest strains are only the sub-product of the wider question -- the difficulties of ploughing ahead with a full calendar in the midst of a global pandemic.

Problems were all but inevitable once the decision was taken to go ahead with the Copa America in June and July -- an extra Copa, the second extra Copa since 2016 and the fourth Copa since 2015. Players and coaches around the continent, especially in Brazil, made it clear that they were playing the Copa under protest.

There were two justifications for their discontent. One was the pandemic. The other was the perception that the time would be better used catching up on World Cup qualifiers, which were behind schedule. Playing the Copa left the continent with 12 rounds of qualifiers still to fit in before the end of March -- and only four rounds of FIFA dates in which to play them.

With two games per round, there was still a deficit of four games. FIFA twice came to South America's aid. An extra FIFA date was established at the end of January. And the dates in September and October were extended to three games, meaning that the players would not arrive in time to play for their clubs at the weekend.

This was one source of conflict with the European clubs. The other was the quarantine restrictions in effect in the United Kingdom -- and also in Brazil. Whether such restrictions are still necessary is a moot point, especially in the case of those who have been fully vaccinated. But these are rules. And they clearly trump any authority that football can come up with -- although this has come as something of a surprise in South America.

The Argentina squad contains four Premier League players -- the Tottenham Hotspur pair of Cristian Romero and Giovani Lo Celso plus the Aston Villa duo Emiliano Martinez and Emiliano Buendia. The squad arrived in Brazil on Friday morning after the 3-1 win away to Venezuela on Thursday.

Just as Brazil is on the UK's 'red list' the reverse is also true. Non-Brazilians who have been in the UK in the past 14 days need to go into quarantine. According to a statement from the Anvisa health authority, these four players did not declare to the local immigration authorities that they had been in the UK in the previous two weeks.

It was clear on Saturday, the eve of the game, that there was going to be a problem. Anvisa were aware of the presence of four Argentines who should have been in quarantine.

How had this situation developed? Football has existed in a bubble in South America. There are still severe restrictions on the travel of private citizens inside the continent. The border between Brazil and Argentina is closed, for example. But football has been given a pass. Even when the pandemic was out of control, with 4,000 a day dying in Brazil alone, international club matches were going ahead.

There have been occasional problems -- team delegations forced to sleep in airports, or matches switched to a neutral country. But the game has gone on. Special dispensations were given in order for the Copa America to go ahead in Brazil.

But, on this occasion,the pass did not extend to those who had recently been in the UK. It was widely expected that a compromise would be reached in this situation. It would all blow over, with the four players perhaps having to undergo an interrogation at Sao Paulo airport after the match.

Brazil's FA declared themselves as surprised as anyone when officials from Anvisa entered the field and put a stop to the game. Down on the pitch there was talk at the time of a deal whereby the England-based Argentina players would be substituted at halftime and could then be taken to the airport.

It is unlikely that Argentina would have agreed to such a deal, and it came across as a desperate attempt to buy time and negotiate further to save the game.

It is unclear why this time a deal could not be agreed with the Brazilian government, who were so keen for the Copa to go ahead at a time when the pandemic was far more severe than now. Everyone involved in the game seemed to count on such an outcome.

There was little or no added health risk from the players competing the game and then heading to the airport. But the Anvisa officials were upholding the rules, and always relying on a last minute reprieve is a gamble that can go wrong. It might do football no harm to recognise that there are limits to its power and influence.