Olympiacos players react after the Champions League opening phase soccer match between Barcelona and Olympiacos in Barcelona, Spain.

Barcelona's Marcus Rashford celebrates after scoring his side's sixth goal during the Champions League opening phase soccer match between Barcelona and Olympiacos in Barcelona, Spain.

Barcelona's Fermin Lopez celebrates after scoring his side's fifth goal during the Champions League opening phase soccer match between Barcelona and Olympiacos in Barcelona, Spain.

Barcelona's Fermin Lopez celebrates after scoring his side's fifth goal during the Champions League opening phase soccer match between Barcelona and Olympiacos in Barcelona, Spain.

Barcelona's Lamine Yamal celebrates after scoring his side's third goal during the Champions League opening phase soccer match between Barcelona and Olympiacos in Barcelona, Spain.

Olympiacos' Panagiotis Retsos, left, holds Barcelona's Marcus Rashford during the Champions League opening phase soccer match between Barcelona and Olympiacos in Barcelona, Spain.

Olympiacos' Ayoub El Kaabi, second left, reacts after scoring a penalty, his side's first goal, during the Champions League opening phase soccer match between Barcelona and Olympiacos in Barcelona, Spain.

Barcelona's Fermin Lopez, background, scores his side's second goal as Olympiacos' Panagiotis Retsos tries to stop him during the Champions League opening phase soccer match between Barcelona and Olympiacos in Barcelona, Spain.

Barcelona's Fermin Lopez celebrates after scoring the opening goal of his team during the Champions League opening phase soccer match between Barcelona and Olympiacos in Barcelona, Spain.

Barcelona's Lamine Yamal controls the ball as Olympiacos' goalkeeper Konstantinos Tzolakis tries to stop him during the Champions League opening phase soccer match between Barcelona and Olympiacos in Barcelona, Spain.