Heartbreak for Cueva as Poulsen struck the decisive goal for Denmark.
Denmark took advantage of some sloppy play from Peru throughout the game.
It was Yussuf Poulsen who got the decisive goal in the 59th minute which helped them win 1-0.
But the South American nation only had themselves to blame as they missed plenty of chances throughout the game.
The most notable mistake was the moment when Christian Cueva miss-hit the first-half penalty, which was awarded after a VAR review.
The Danish national side will forever be thankful to their goalkeeper Kasper Schmeichel, who made six saves and now hasn’t conceded a goal in international football for 534 minutes.
Peru will take on France next, who themselves have not played well earlier today but somehow managed to scrap out the dirty win with goals from Antoine Griezmann and Paul Pogba.
Meanwhile Denmark will go into their game against Australia in confident mood after collecting three points.
The result leaves Denmark joint-top of Group C with France.