Southgate said he was unsure if that was the case, but that there was no questioning what the Tottenham striker had brought to the team both on and off the pitch in Russian Federation.
And the former Everton boss is likely to take this game quite seriously as he looks to end the Red Devils' World Cup campaign on a high.
At England's first two group games there were only about 2,000 fans present each time, but as fears of hooliganism and violence in Russian Federation have so far proved unfounded, and Gareth Southgate's team have progressed further in the tournament than most expected, the dash to Moscow commenced.
But the team's performance over the past month - with a 6-1 trouncing of Panama, their first ever World Cup penalties win and first World Cup semi-final since 1990 - has seen them reconnect with a disillusioned fan base.
And Croatia would never let England get so close again.
Had Kane added to his six goals in Russian Federation with either of his back-to-back chances in the first half against Croatia on Wednesday, when England was dominating and led 1-0, he could yet be lifting the trophy on Sunday.
Southgate said playing regularly in big matches was a key stage of development for his players and that the way they dropped away in the second half was perhaps a result of their inexperience.
"England we're proud of you, that's all I've got to say".
"Semi-finals, they've done what they had to do, they took us to the semi-finals". "The only disappointment was that we were 1-0 up, and we should have been more".
Parv Moondi, 49, from Norwich, was heading out of the Luzhniki and back to central Moscow. We have two days to prepare.
"I just feel so disappointed". I think it is too easy to move on immediately from what we've just been through.
"This was the dream, we could've made it".
"They played their best, it obviously wasn't to be".
Football fans in Reading had a traumatic evening as they went through all the emotions as England crashed out of the World Cup. He said: "I'm gutted. In extra-time we showed we are still able with the fatigue to play our game".