Yussuf Poulsen scored the only goal in the second half to give Denmark a 1-0 win over Peru, who earlier missed a penalty in their Group C opener on Saturday.
Peru, making their first appearance at a World Cup in 36 years, were granted a penalty just before halftime following a video review as Poulsen dragged down Christian Cueva, who skied his spot kick well over the bar.
The South Americans continued to attack in the second half and nearly opened the scoring in the 57th minute but Andre Carrillo and Edison Flores missed chances in a goalmouth scramble.
Denmark made them pay two minutes later on the counter-attack as Christian Eriksen laid the ball of for Poulsen to finish inside the near post.
Peru brought captain Jose Guerrero off the bench and attacked steadily for the rest of the game, but they saw numerous opportunities in front of goal go astray.
Guerrero’s header was saved by Kasper Schmeichel in the 64th minute, and 15 minutes later the captain’s audacious backheeled attempt beat the goalkeeper only to roll wide by inches.
Schmeichel then stopped a point-black attempt from Jefferson Farfan, and Denmark also went close when Eriksen was played in but Pedro Gallese did well to save.
Peru ultimately could not find an equaliser and Denmark joined France on three points atop the group.