Southgate tomorrow takes his team into the biggest game the country has seen since the 1990 semi-final.
England fans have been warned against alcohol-fuelled "senseless behaviour" after police dealt with hundreds of incidents following the team's quarter final victory over Sweden.
"We've got to keep getting over those hurdles and I know we talked about the success of the younger teams but this is a much harder, much bigger level for the players and the belief is building as things are happening".
Subasic suffered a tight hamstring towards the end of Croatia's quarter-final win over hosts Russian Federation and was unable to take goal-kicks before the tie went to penalties.
"We've made several pieces of history".
"If Southgate wins the World Cup he 100% deserves a knighthood", Ross Patrick, the man behind the idea, told the Press Association. We know what's at stake and in such moments you forget any fatigue you may feel because this is maybe a once-in-a-lifetime opportunity.
"Football's coming home.I couldn't listen to it for 20 years, frankly", Southgate said.
England will play Croatia at Moscow's Luzhniki Stadium at 7pm United Kingdom time.
Asked what is was all about, a slightly bemused Southgate said: "That's exactly what I asked our fitness coach a well, 'What is that all about?'". Everyone has been out on the streets celebrating what we've achieved and that is a great source of pride for us.
"I remember people saying he's going to be a one-hit wonder and he's just completely proven them wrong and blown it out the water".
"This generation has been underrated due to their results but they've had the quality and now they are showing it".