South America's home-field advantage like no other

The most competitive World Cup qualification campaign on the planet reaches the halfway stage Friday when South America plays its ninth round of matches. Just three points separate Argentina at the top of the table from Venezuela down in sixth place. No one is making up the numbers. Every game resonates with relevance and rivalry. There are no foregone conclusions – and no such thing as an easy away game.

The last round a month ago was unusual in that its four matches comprised two draws and two away wins. Normally the outcome is far less kind to the road team. The usual ratio of home wins to away wins in the South American qualifiers is 3-to-1 – almost borne out by the first eight rounds, which have contained a total of 18 home wins to seven away. Away wins are customarily twice as common in the European qualifiers – and once more that pattern has been repeated in the early stages of the 2014 campaign, where so far in Europe there have been 22 home wins and 16 away.

So why is life so tough for the road team in South America? One explanation is that it is a mighty long road. Distances are vast in South America, and traveling around the continent can be tiring. At the end of the journey, the visiting team is often met by an intimidating atmosphere – and conditions that may not be to its liking.

Especially altitude. The Andes mountain range snakes along western South America. Bolivia and Ecuador have their fortresses high in the hills. Ecuador play at Quito, some 2,800 metres above sea level. Bolivia's base is even higher. La Paz stands 3,600 metres above sea level.

Given three weeks anyone can acclimatise. Without that time, a footballer unused to the conditions loses a significant part of his athletic capacity in the rarefied air. He finds himself gulping for oxygen. On a visit to La Paz a few years ago, Argentina's defenders found themselves unable even to shout instructions to their forward line. Last time out, in the early days of Diego Maradona's reign as coach, Argentina made no specific preparations for playing at La Paz. Instead, Maradona concentrated on the psychological aspect, trying to convince his team that it could play its normal game away to Bolivia. Argentina lost 6-1.

Both Ecuador and Bolivia pick up the bulk of their points up in their mountain strongholds. In the current campaign, for example, Ecuador have won all four of their home matches. Neither they nor Bolivia has managed to win on the road. Is it fair that they are permitted to play at altitude? Home advantage is part of the game, but how much home advantage is too much?

These are points that have been hotly debated in South America, especially when Brazil's football authorities tried to lead a campaign to ban international matches at altitude.

It was never likely to succeed. On the one hand, it flew entirely against the prevailing spirit in favour of extra South American integration, meaning that in political terms it was a non-starter. True, Ecuador could play their matches at sea level (at Guayaquil), as could Bolivia (at Santa Cruz). But what of the clubs that are based at altitude? What should they do? Cease to exist?

Moreover, for play in altitude to be banned, conclusive evidence would have to exist to the effect that it is not only a source of discomfort to the unacclimatised player, but that it is a genuine health risk. No such evidence has yet come to light. It does seem clear, though, that extreme temperatures can constitute such a risk – but even World Cup matches have kicked off at midday in intense summer heat. As long as extreme heat is considerable permissible for football, there can be no possible case against altitude.

These issues loom large in Friday's matches. Both Bolivia and Ecuador are at home, in La Paz and Quito respectively. Their opponents, though, will consider themselves better equipped than most to meet the challenge of altitude.

Chile, who visit Ecuador, have a good record in such conditions. They have already won away to Bolivia in the current campaign, for example. The Andes pass through Chile, whose players have some exposure to altitude and usually adapt well in physical, psychological and tactical terms. They will see the main threat as not the conditions but the attacking firepower at Ecuador's disposal – and they will heave a sigh of relief that Ecuador's star man, Luis Antonio Valencia, will miss the game through suspension.

Peru will have no fear when they climb up to face Bolivia in La Paz. True, Peru's capital, Lima, where most of the traditional clubs are based, is at sea level. But Peru also has an Andes region, with some first-division clubs based high in the clouds. Coach Sergio Markarian has assembled a special squad of altitude specialists for this game. Next Tuesday, the old guard will return for the trip to Paraguay. But the team to face Bolivia will largely be drawn from the Cuzco clubs Cienciano and Real Garcilaso, full of players who will feel no discomfort and who are accustomed to the quicker movement of the ball through the rarefied air.

Also at home on Friday are Colombia, another country with a mountain capital. Bogota stands some 2,600 metres above sea level. But the city will not stage the match against Paraguay. In recent years Colombia have been frustrated whenever they have used Bogota as their base. Results have been disappointing. When they have qualified for the World Cup it has always been with a base at Barranquilla, a swelteringly hot city on the Caribbean coast. A month ago, Colombia made things far too hot for Uruguay, who lost their long unbeaten record with a crushing 4-0 defeat. Now they hope to do the same to Paraguay, and add another home win to those South American statistics.

Tim Vickery is an English football journalist who has lived in Brazil since 1994 and specializes in South American football.