Riera was born in Santiago, Chile. As a footballer, he played for Chile in the 1942, 1947 and 1949 Copa Américas. He also played at the 1950 FIFA World Cup, and managed them on home soil to a third place in the 1962 World Cup. In 1962–63, Riera led Portuguese side Benfica to the Primeira Liga title. He returned to the club in 1966 and led them to another [[1966–67 Primeira Divisão|champions title]]. In the [[1963 England v Rest of the World football match]], Riera coached the [[World XI|FIFA World XI team]]; it was the first FIFA XI team in the history of the game. In Chile, he left a legacy with disciple coaches such as [[Arturo Salah]] and [[Manuel Pellegrini]], leaving a tradition and an identity for Chilean football. Riera died in his home city, [[Santiago, Chile|Santiago]] of an apparent heart attack.