The injuries started to pile up, legs looked gassed and the opportunity to seal it became reality for Mandzukic, who sneaked behind the back of England defender John Stones to score the victor.
"But the team will be stronger for that and as we reflect over the next few days, there will be a lot more positives".
England's Kieran Trippier (not pictured) scores their first goal from a free kick past Croatia's Danijel Subasic.
England were hoping to reach a first World Cup final since 1966, but let an early lead slip to lose 2-1.
According to Federation Internationale de Football Association, the players "continued to display unauthorised commercial branding on playing equipment items before and during the quarter-final match between Sweden and England".
Croatia's legs at the start seemed to carry the weight of so many minutes in the knockout stage, and a pressing England went up quickly.
"He will be under the most glaring spotlight imaginable as he leads the Croatia defence in their World Cup semi-final against England, and the sight of Harry Kane lining up against him once again might just unnerve him".
In Moscow, Croatia fans said they were taken aback by their side's win. We have done that today in extra time. It's been a fantastic journey.
"I think in the first half, we were really good and we maybe could've got another and in periods throughout the game we had chances".
"We've come an incredibly long way in a short time and the experiences against Colombia, Sweden, is probably beyond where we thought we could go".
"All these words from them we take, we were reading and we were saying 'OK, today we will see who will be exhausted.' As I said, they should be more humble, and respect opponents more". There will be legitimate questions about how much they have left in the tank.
But he is yet to fully convince and win the trust of everyone, and is still susceptible to occasional errors, highlighted by his stray pass that allowed Russian Federation a chance to go clear on goal in the closing minutes of the quarter-final.
And then with Cortez flat on his back on the Luzhniki Stadium pitch, he offers him a helping hand and brings him back to his feet.
It was a painful defeat for Belgium, foiled at the semifinal for the second time in their history, as the clock ticks on their so-called "golden generation" of players.
However, this time he was far more direct, playing on the last shoulder of the Croatian backline and zooming off towards goal rather than retreating away from it.