The Danes finished second in Group C, setting up the tie with the Group D winners.
Croatia booked their spot in the knockout stages with a 2-1 victory over Iceland, propelling them to the summit of their group having made it three wins from three.
Ivan Perisic scored in the 90th minute to win it for Croatia after Gylfi Sigurdsson had pulled Iceland level from Milan Badelj's opening strike.
Elsewherein Group D, Argentina set up their mouth-watering tie with France after completing the group stages in second, thanks to a 2-1 victory over a spirited Nigeria side.
Manchester United defender Marcos Rojo produced a late volley to deny the African nation after Victor Moses had cancelled out Lionel Messi's opener from the spot.