Flamengo's Thiago uses an oxygen mask during a special training session in which the team used a controlled air supply to simulate the conditions in the Bolivian city of Potosi, the world's highest city at nearly 4,100 meters (13,451 ft) above sea level, where they will play their first Copa Libertadores soccer match against local club Real Potosi next Wednesday, at their training headquarters in Rio de Janeiro February 8, 2006. REUTERS/Bruno Domingos (BRAZIL)