FC Nordsjaelland had not won in the Parken stadium in seven years, and it looked like they were headed for another disappointment when the home side took the lead after only six minutes when Mohamed Elyounoussi intercepted a back pass from Noah Markmann and kept his cool to slot the ball into the net past goalkeeper Andreas Hansen.
After 30 minutes, FC Copenhagen came close to doubling the lead, but Elias Achouri squandered the chance after a clever heel-pass from Elyounoussi. Also, FC Nordsjaelland were unfortunate not to restore parity when Ola Solbakken's wonderful volley missed the target by inches.
After 70 minutes, the game was turned upside down within seconds when Birger Meling was sent off for blocking a close-range finish from Alexander Lind, and Solbakken subsequently converted the penalty.
Eight minutes later, bad turned to worse for the reigning champions when Pantelis Hatzidiakos made a grave error following a corner to leave Prince Junior with acres of space and with only FC Copenhagen goalkeeper Dominik Kotarski to beat, the Ghanaian made no mistake to seal a sensational win for the away team in the Parken Stadium.