Speaking after the 21-year-old was linked with a January move to English Championship side Derby County, Levein admits he has been thrilled with Souttar’s progression after being written off during his late teens.
Souttar has formed a robust defensive partnership with Scotland internationalist Christophe Berra and is part of a rearguard that is hoping to record a sixth successive clean sheet for the first time in the club’s 143-year history at Aberdeen this afternoon.
After initially making the breakthrough under much fanfare as a 16-year-old at Dundee United, Souttar’s form suffered during the latter part of his time at Tannadice as the team also struggled.
However, Levein has been hugely impressed by how the Scotland Under-21 defender has proved his detractors wrong since transferring to Tynecastle nearly two years ago.
Levein said: “I thought that was his best game for Hearts [against Hibernian in Wednesday’s 0-0 draw], I really did. I think he’s brilliant.
“When we signed him, I hoped the trajectory would be up the way and it has been.
“He was out eight months with an Achilles injury and he spent that time in the gym working his backside off.
“Physically, he is a different specimen altogether and people don’t realise that’s he really quick.
“His passing is something that everybody admires, it’s one thing he is brilliant at. I think he is a complete player, I really do.
“I think John Souttar is another window away from being ready to go anywhere, he needs a full season of this and then I think he might be ready.
“He’s our most valuable asset for sure. We’re in a position that we don’t need to sell so that always helps.”
Levein, pictured, insists Souttar has now also proved he has the physical attributes to be a successful centre-half.
He added: “All he has been doing is learning. People had written him off at 17 and 18 years of age, saying he couldn’t do it.
“Until I was 21, 22 years-old, I didn’t feel I could dominate centre forwards because, physically, I wasn’t capable. I was quick and I could recover, get in behind and tidy things up but trying to win headers against experienced centre-forwards, who know what they’re doing – for a centre back that was really difficult.
“He has gradually been getting better week-in, week-out and he hardly lost a header the other night. I honestly think he could be anything.”
While Levein is hoping to retain Souttar, who is contracted until 2020, until at least the end of the season, the former Scotland manager admits playmaker Jamie Walker’s departure could be imminent.
English League One side Wigan are keen to recruit the 24-year-old and are said to be ready to pay £300,000 for a player whose contract expires in May.
However, Levein’s interest in Latics midfielder Jack Byrne, who is currently on loan at Oldham, and Walker’s knee injury are other factors to be taken into account.
He added: “He picked up a knee injury during the Hibs game and he’s away for a scan today.
“There’s been some interest in Jamie from Wigan but I honestly couldn’t tell you if Jack would be part of that deal.
“It’s quite complicated and obviously it’s even more complicated now that Jamie’s hurt his knee. I don’t know how any injury would affect things because discussions haven’t involved that. There’s nothing done or decided.”
Levein, meanwhile, is hoping to extend Jon McLaughlin’s one-year contract after being impressed by the former Burton Albion goalkeeper’s presence at the back.
Levein, who confirmed that Connor Randall broke his hand in Wednesday’s goalless draw with Hibs and could also be without Prince Buaben and Ross Callachan for the trip to Pittodrie, added: “He has been brilliant and that’s [the contract] something I’ll speak to him about. We’ve got a lot of things going on but he’s done a really good job and he’s a good boy.
“He’s come in and done exactly what I hoped he would do, which is use his experience, be calm and assertive.
“He makes saves but they all do that. It’s the other part of the game and he’s definitely brought a calmness to us.”