The death of a Bolivian referee officiating a match at more than 4,000 meters above sea level has reopened debate about the safety of playing soccer at such altitude.
Victor Hugo Hurtado collapsed while refereeing a Bolivian first division match between local side Always Ready and visitor Oriente Petrolero last Sunday in El Alto, at 4,090 meters,
Hurtado went into cardiac arrest and was stretchered from the field before being taken to hospital, where he died following a second heart attack.
He was 31.
El Alto's municipal stadium is the highest in the world that is home to a professional soccer team, according to a banner outside the ground.
It is more than 400 meters higher than El Hernando Siles stadium (3,660 meters) in nearby La Paz that is used by the Bolivian national team.
But Always Ready's club doctor, Erick Koziner, insisted altitude played no part in Hurtado's death.
"There was no pulmonary edema, that is the first thing observed in altitude sicknesses before it passes into the cardiac system," Koziner said after performing an autopsy.
Bolivia's soccer federation president Cesar Salinas told Diez.com website that "people inside and outside who don't like us will try to use this incident" against Bolivian soccer.
He said tests have previously "proved" playing at altitude "has no effect."
One of Hurtado's cousins, Orlando Herrera, told local media the referee was accustomed to altitude as he had previously lived in El Alto, once a sprawling La Paz suburb.
Pedro Saucedo, head of Bolivia's refereeing commission, told Los Tiempos newspaper Hurtado had displayed "no signs of tiredness, nothing suspect" at half-time.
Back in 2007, FIFA suspended all matches above 2,500 meters after some of Bolivia's rivals in South America complained that the host - which has only qualified for the World Cup three times - had an unfair advantage in La Paz.
A month later a special exemption was made for the "Condor's Nest" in La Paz before the ban was overturned a year later.
But that hasn't changed opinions. Two years ago, Brazil superstar Neymar posted a picture on Instagram of him and his teammates wearing oxygen masks ahead of a match against Bolivia.
"Inhuman to play in these conditions. Pitch, altitude, ball ... everything is bad," Neymar wrote.
After the match, a 0-0 draw, Manchester City forward Gabriel Jesus said he "felt a little tired ... it wasn't nice."
Bolivia was briefly banned from playing in La Paz in 1993 after Brazil lost a 40-year unbeaten record in World Cup qualifiers in a 2-0 defeat to the plucky minnow. Brazilian Joao Havelange was the president of FIFA, world soccer's governing body, at the time.
The subject came up again in 2009 after an Argentina side coached by Diego Maradona and starring Lionel Messi was humiliated 6-1 in a qualifier for the 2010 Word Cup.
Maradona was one of those who criticized the FIFA ban two years earlier.
Whether playing at such an altitude is dangerous or not, there is no doubt it provides the home team with an advantage.
Bolivia's record at home is leaps and bounds better than its efforts on foreign pitches.
In World Cup 2018 qualifying, Bolivia lost every away match, but at home it managed four victories and a pair of draws in its nine games, even blanking mighty Argentina 2-0.
High-altitude pitches are not uncommon in this Andean nation, where Potosi's two teams - Nacional and Real - play at 3,990m in Victor Agustin Ugarte stadium, while San Jose plays in Jesus Bermudez stadium in Oruro, which is at 3,731m.
While Hurtado's death will undoubtedly heighten concerns about the safety of playing at such altitude, Bolivia's soccer federation has decided to act quickly to clear up any doubts.
"We have already taken the initiative to invite four specialists in the field to issue a very clinical and very medically-accurate report," said Salinas.