Out of contract at the end of the season, the 25-year-old is free to agree a pre-contract with any of his many admirers come January.
Hearts refused a pay-off in the summer, believing there was greater value in having him in their backline as they sought to get off to a winning start in their return to the Premiership.
But with every starring performance, at club and now international level, the inevitability of his departure moves more clearly into focus.
“The better the team does, and the higher up the league they are, it’s harder to keep all the players. It’s just part of football and something you have to accept,” said Neilson, who was delighted to see Souttar named man of the match as Scotland booked a home play-off spot in the ongoing quest for a place at the 2022 World Cup. He was also relieved to see him come through the outing unscathed as Hearts look ahead to this weekend’s trip to Motherwell.
“I was delighted for him. I thought he did really well,” said the Tynecastle boss. “To be honest, I didn’t realise it was him that scored. I was at the game and it wasn’t until a couple of minutes later that I realised. I’m just delighted for John because he’s had a hard couple of years.
“It just shows that you need to keep fighting to come back. Three injuries and he’s managed to get back to probably as good as he’s ever been. Scoring against Denmark at Hampden in front of a full house – it doesn’t get much better than that.”
The level of performance did not surprise a manager who is still hoping sporting director Joe Savage can pull off a miracle and find a way to convince Souttar to sign a new deal in the capital.
“We’re speaking to him. There are a number of players we’re speaking to but that’s the way football is. It goes back and forward, back and forwards. Joe is still dealing with it, still trying to see if we can get some sort of agreement on it.
“John is a good player. I still think there is a lot more to come from him. When I was here previously, he was a young kid, but he was still a top player. When I look at him now, I think there is more in there. We’re pleased with him but it’s back to Fir Park on Saturday.”
They travel through, followed by around 3500 Hearts fans, hoping to recapture the fight and the flow of their winning performance against Dundee United ahead of the international break.
“We were pleased to get the result against United but it’s always difficult at Fir Park,” Neilson added.
“But, it’s phenomenal the support we’ve been getting and long may it continue. If the players keep working the way they are and winning games, being entertaining, the fans will keep coming along.”
