19:00 BST, Sunday 1 July, Nizhny Novgorod Stadium (Nizhny Novgorod, Russia), ITV1
Luka Modric and Ivan Rakitic have proven to be the best central midfield partnership at this World Cup and that has helped them propel Croatia into the last-16 with ease. They have won all three of their group games, including a 3-0 demolition of one of the pre-tournament favourites Argentina.
Denmark are also unbeaten, though they have won just one game at the tournament so far and that came in their opening fixture against Peru. Two successive draws - coupled with a drop in creativity - have since followed for the Danes as they finished second behind France in Group C.
Croatia have netted seven times and conceded just one goal at the tournament, whilst Denmark have scored just twice and conceded just once.
Could this be a battle of the defences as both seek their first quarter-final appearance since 1998.
Last Time Out
Croatia 2-1 Iceland
Milan Badelj and Ivan Perisic scored the important goals against Iceland that gave Croatia maximum points and first place in Group D. Iceland needed a victory to keep their hopes of qualification alive, but they struggled to deal with Croatia all game and were deservedly beaten.
Gylfi Sigurdsson did, however, ensure Croatia conceded their first goal of the tournament as he netted a penalty after 76 minutes. Perisic got the winner in the 90th minute to confirm Iceland’s exit and Croatia’s 100% win record, however.
Denmark 0-0 France
The less said about this game the better as both sides were happy to settle for a point and bore the poor people in attendance to sleep.
Denmark needed a point and got it, though they could have easily have forced the issue as Australia went a goal down to Peru early in the afternoon, so they knew their own fate was not reliant on results elsewhere.
Zlatko Dalic made a host of changes to avoid injury and suspension against Iceland, but expect these names to come back into the side in the last-16.
Reverting back to the side that dismantled Argentina 3-0 in the group stage, Marcelo Brozovic will return to shield the defence with goal-scorer Milan Badelj dropping to the bench. Mateo Kovacic will have to give way for Ivan Rakitic, whilst Dejan Lovren comes back into defence for Vedran Corluka.
Croatia still won last time out despite making changes, so it is possible that some of those fringe players have won a place in the starting XI, but it is hard to see him dropping anyone from that magnificent Argentina win.
With Denmark struggling in front of goal and reliant on Christian Eriksen, Age Hareide could make offensive changes to get the best of his team, though it's a case of finding continuity with those that have made it this far.
Kasper Dolberg may start up front as he came on last time out and did reasonably well. Yussuf Poulsen is likely to come back into the side ahead of Martin Braithwaite after serving his suspension, whilst William Kvist is still injured.
Key Battle: Marcelo Brozovic (Croatia) vs Christian Eriksen (Denmark)
Given the defensive strength of both sides, this game is likely to be settled by extremely fine margins, and trying to get that edge for the Danish is Christian Eriksen.
Denmark's creator-in-chief, Eriksen has had a hand in both of their World Cup goals - one goal, one assist - and is involved in everything positive the Danish do going forwards.
KEY STAT: Christian Eriksen has been involved in 18 goals (scored 13 and assisted five) in his last 16 appearances for Denmark.
Croatia, however, have a system in place to stifle these types of creative influences. Eriksen likes to get in between the lines of attack and midfield, but Croatia's 4-1-4-1 compensates for such players with Marcelo Brozovic prowling the space between his back four and midfield.
With Age Hareide prioritising a defence-first tactic, it's left Eriksen looking isolated at times and it'll require a moment of magic to get past Brozovic without support, who was highly effective in suffocating Lionel Messi out of their group game.
The winner is the dark-horse
Whoever progresses from this game will then be given the tag of World Cup dark-horse heading into the quarter-finals. Neither side have realistic hopes of winning the competition, but once you reach the last eight, you never know...
In 2002, South Korea and Turkey were the shock semi-finalists. In 2006 Ukraine made it to the quarter-finals and in 2010 it was Uruguay who were the unexpected semi-finalists. The World Cup always has a surprise side going further than we thought, and whoever wins this fixture will be given that reputation.
The role of Mario Mandzukic
The one disappointment for Croatia so far is that their star striker Mario Mandzukic has failed to score a goal. He was rested last time out against Iceland, but his performances in general have lacked that quality that we are so used to seeing from the 32-year-old.
Just one goal since 2016 for his country, Mandzukic will need to improve upon that record if Croatia are to go past the last-16.
Outside of his goal-scoring, Mandzukic does serve a crucial purpose in the side. He's a nusiance in the box and not only provides a target for set piece routines, but as a means of reliving pressure via a counter-attack.
He's brilliant at holding the ball up and brining others into play and, as long as Perisic and his teammates continue scoring, Mandzukic's drought isn't of much concern.
Prediction: Croatia 2-0 Denmark
Denmark are a good defensive side, but one that lacks the attacking quality - beyond Christian Eriksen - to get past a strong Croatia side.
The spine of this Croatia team is so strong, and they have been arguably the standout and most consistent performers of this competition so far. They have nothing to fear against Denmark and, for that reason, they should get into the next stage of the competition.
Listen to the RealSport football writers discuss all the action from Day 16 of the World Cup in Kremlins in the Basement: RealSport’s daily World Cup podcast.