Cobresal conceded a last-gasp own goal as Corinthians kicked off their Copa Libertadores campaign with a 1-0 win.
The Group 8 clash in Chile was petering out for a draw until Miguel Escalona turned the ball into his own net in stoppage time on Wednesday.
Corinthians attacker Lucca whipped in a low delivery across the six-yard box and Escalona's effort to clear the danger saw him poke the ball past goalkeeper Leonel Cuerdo at the near post.
The win moved Corinthians top of the standings after Cerro Porteno and Santa Fe played out a goalless draw on Tuesday.
Brazilian rivals Sao Paulo were not as fortunate, going down 1-0 to The Strongest in Group 1.
Sao Paulo, who reached the last 16 last season, lost out to their Bolivian visitors after Matias Alonso broke the deadlock in the 62nd minute.
Alejandro Chumacero scooped the ball up over keeper Denis for Alonso to head into an empty net from inside the six-yard box.
Atletico Mineiro were also victorious away from home thanks to a 2-1 win at Melgar.
All three goals came in the first half as Mineiro duo Rafael Carioca and Patric cancelled out Omar Fernandez's 14th-minute opener in Peru.
Mineiro top Group 5, with Colo Colo and Independiente del Valle yet to open their campaigns.
Meanwhile, Enrique Triverio's brace helped 10-man Toluca past Gremio 2-0 in Group 6.