By Tim Vickery
South American football reporter
Flamengo's first complaint is that extreme altitude gives the home side an unfair advantage
Just one week into the Copa Libertadores, South America's Champions League, the competition has already run into a problem as big as a mountain.
Last Wednesday Flamengo of Brazil climbed 3,800 metres into the Andes to face Bolivia's Real Potosi.
The visitors clawed their way to a 2-2 draw, but such exertions in the extreme altitude took their toll.
Towards the end of the game several Flamengo players needed oxygen. Others complained of feeling unwell.
Now the competition has been left with a headache.
The next day Flamengo issued a statement declaring that the club would not take part in any future matches played at altitude.
The cut off point they appear to want to impose is 1,500 metres - which, in this year's competition would exclude some teams from Ecuador, Peru and Mexico, as well as the Bolivians.
It would mean no games in Quito, Ecuador's capital, or Mexico City, scene of some of the greatest World Cup matches.
The principal targets, though, remain the teams from Bolivia.
This is only Potosi's second Libertadores campaign. But Bolivar, the biggest team from La Paz (3,600 metres) are competition stalwarts, and their city rivals The Strongest are frequent participants, though they have failed to qualify this year.
Flamengo's first complaint is that extreme altitude gives the home side an unfair advantage.
This is certainly true. Without three weeks of adaptation time the player unaccustomed to altitude loses a significant part of his athletic capacity in the rarefied air.
Taking the expansion of the Libertadores seven years ago as a starting point, the statistics bear out the point.
If it's become a case of choosing where you want to play we'll request that we don't have to play in the heat
Together, Bolivar, The Strongest and Real Potosi have played 40 home games, recording 25 wins, nine draws and six defeats, scoring 78 and conceding 41.
By contrast, their away record is a chamber of horrors - 38 games, one win, two draws and 35 defeats, with 21 goals for and 104 against.
Indeed, The Strongest and Real Potosi have lost all of their away matches.
There is not the slightest doubt, then, that extreme altitude tips the balance towards the home side.
These figures, though, tend to suggest that over-reliance on altitude is not doing Bolivian football any long term favours.
Flamengo's second complaint is that playing at altitude puts the lives of the players at risk.
Here they are on less comfortable ground.
The indications would seem to be that playing in conditions of extreme heat - as Flamengo do in their home city of Rio de Janeiro - is probably more dangerous.
Colombian physical trainer Diego Barragan has considerable experience of getting teams ready for the trip up the Andes to Bogota, or to the sweltering port of Barranquilla.
Last week he commented "it's much more difficult to prepare players for heat than for altitude."
A Potosi director responded to Flamengo's threat by saying "if it's become a case of choosing where you want to play, we'll request that we don't have to play in the heat."
His side can expect a warm welcome when they visit Rio for the return match in mid April.