Second-half goals from Thorgan Hazard and Kevin de Bruyne saw Belgium complete a remarkable comeback after being 1-0 down inside two minutes. The result puts the Danish side's chances of qualifying for the knockout stage in peril.
Denmark, who unfortunately saw their star man Christian Eriksen suffer a life-threatening injury in their opening game, were the better side in the first half. They pressed high and seemed to have rattled Belgium from the start.
Their remarkable energy levels quickly paid off as they took the lead in the second minute of the game. Pierre-Emile Højbjerg capitalized on a wayward pass from Jason Denayer and sent Yussuf Poulsen in to finish.
Denmark kept up the tempo for most of the first half and largely left their opponents trailing in their wake. Belgium recorded just one shot in the first 45 minutes.
The Red Devils knew they needed a spark. Coach Roberto Martinez sent Kevin de Bruyne on at halftime and the Manchester City man did not disappoint.
De Bruyne bagged an assist less than 10 minutes after his introduction. He set up Thorgan Hazard with a brilliant pass to restore parity.
The Manchester City man then went on to clinch the game with a 70th minute winner. A neat Belgian passing move found de Bruyne in space and he rifled a shot with his left foot past Kasper Schmeichel to give Belgium the lead.
The Danish side finally got a grip on the game after falling behind and piled the pressure on their visitors. Barcelona man Martin Braithwaite hit the crossbar late in the game and forced Thibaut Courtois into some good saves. But Denmark were unable to find an equalizer and now have no points after two matches.
Belgium face Finland next in their final game of the group stage with the Finnish side in need of a win to advance. Denmark, meanwhile, play a must-win match against Russia, who need a draw to advance. On that note, here are five talking points from the game.
#5 Denmark fail to capitalize on early pressure
An uncharacteristic error from Schmeichel in goal and a missed penalty from Højbjerg saw Denmark fall to a 1-0 loss against Finland.
The Danes knew they needed a win against table leaders Belgium to keep their Euro 2020 dream alive and started the first half energetically.
Their relentless pressing saw them take an early lead in the game through Poulsen. However, Denmark were left to rue their missed chances in the end. The Danes could have been three goals up in the first half but their waywardness in front of goal, coupled with some brilliance from Courtois, saw them head into the tunnel with only a one-goal lead.
A big was missed by left wing-back Joakim Maehle as he failed to convert after a scramble in the box. The Atalanta defender then created another good chance for his fellow wing-back Daniel Wass, but the Valencia man failed to direct his close-range header past Courtois.
They also created some excellent chances in the second half and constantly worried the Belgium defence. However, Denmark failed to capitalize on their dominance and now have an uphill task ahead of them.
#4 Mikel Damsgaard impressive against Belgium
Damsgaard was brought into the starting XI as a direct replacement for the absent Eriksen and the 20-year-old did not disappoint.
The winger, who made his international debut in November last year, played for the first time in a major tournament. Damsgaard was lively throughout and caused Belgium all kinds of problems.
Starting on the left, the Sampdoria man created two chances while also completing a joint team-high five dribbles.
Although he was substituted right after Belgium took the lead, the young winger was easily one of Denmark's better players on the evening. He can hold his head high after a wonderful performance against one of the big boys.
#3 Race for qualification in Group B becomes tricky
Had the game ended in favor of Denmark, all four teams in Group B would have had three points going into the final fixtures of the group stage.
However, with Belgium clinching all three points, Roberto Martinez's men have secured a place in the knockout stages. Only one spot remains for automatic qualification from the group.
Denmark face Russia next week in a game that is bound to be highly engaging. Russia won their first game of the tournament with a slender 1-0 win over Finland earlier on Thursday. They lost 3-0 to Belgium on Matchday 1.
Although the Russians currently sit in second place with three points, they have the same goal difference as Denmark. For Denmark to advance to the next round, they need to win against the Russians on Monday and hope Belgium defeat Finland.
Russia, however, know that a draw would be enough to see them through and might play for a point. Simultaneously, Belgium could field a rotated squad against the Finns having already secured qualification.
Both of these possibilities do not bode well for Denmark's chances but will undoubtedly make the race for qualification in Group B more interesting.
#2 Belgium bounce back after slow start
Belgium have been widely touted as one of the favorites to win this edition of the Euros. They hype is justified as they currently sit at the top of the FIFA rankings.
However, their first-half performance was rather dreadful and uninspiring. They did not look convincing at all in the first 45 minutes as they failed to match the urgency and zest of the Danes.
Belgium boss Martinez made the right decision to bring on de Bruyne at the start of the second half. The midfielder's introduction automatically improved the Red Devils' performance as they began to play with far more confidence and drive.
Less than 10 minutes into the half, they had leveled the scores. Martinez also brought on Eden Hazard and Axel Witsel soon after to capitalize on their momentum. The move worked to perfection as Hazard and de Bruyne combined to give Belgium a deserved lead which they saw out in the end.
#1 A Kevin de Bruyne masterclass
de Bruyne suffered an injury to the nose during Manchester City's clash against Chelsea in the Champions League final last month. He has been out of action since then.
The midfielder missed Belgium's opening game against Russia. Although his team-mates comfortably clinched a win then, they desperately required his services against Denmark.
After struggling to create any chances in the first half, de Bruyne was brought on at halftime and immediately got down to business.
He provided the assist for the equalizer after a fantastic run by Romelu Lukaku. de Bruyne took a deft touch in the box to leave two Danish defenders on the ground before squaring the ball to Thorgan Hazard for a tap-in.
The Manchester City man then scored one himself, striking a low shot with his weaker left foot past Kasper Schmeichel. After looking disoriented in the first half, Belgium now had the lead and it was all thanks to de Bruyne.
In just 45 minutes, the midfield maestro created two big chances and registered a team-high five dribbles. de Bruyne also played a starring role in both goals to send his country into the Round of 16 of Euro 2020. On the night, what we witnessed was a true masterclass from a modern football great.