Four operations, altitude chambers and sessions described as "absolute torture" helped Harry Souttar return for the World Cup — and could help answer the one question Sheffield United still have about a potential reunion.

Harry Souttar has opened up on the "absolute torture" he put himself through to get back fit for the World Cup this summer - with Sheffield United hoping that the giant defender’s gruelling work can provide the answer to a potential summer transfer dilemma.

The Australia international remains a player admired at Bramall Lane after his successful loan spell with the Blades in the first half of the season before last, before a serious Achilles injury brought his season to a premature end. Souttar's quality has never been in doubt, especially at Bramall Lane.

But it is his fitness that has become the question that any interested club must answer this summer, following Leicester City’s drop into League One. They are expected to trim their wage bill, while United need defenders. Souttar's leadership, aerial dominance and Championship pedigree make him an obvious fit.

But after another serious injury setback, there has to be confidence that the 6ft 7in centre-half can withstand the demands of a long season. His inclusion, therefore, in Australia's World Cup squad was significant.

Not because he needed to prove anything in terms of his ability; but because every appearance is another indication that his body, after months of rigorous rehabilitation, is holding up. Speaking recently to Football360, Souttar outlined the lengths he went to in order to make sure he was on the plane.

"A typical week would be a lot of physio in the morning before the lads got to train," he explained. "Then I'd go in the gym and do the first hour or two hours injury-specific just on the Achilles. Then I'd either have an upper-body session or a core session. Then a bit of lunch and in the afternoons it would be conditioning.

"I'd be in the heat chamber on the assault bike. That was absolutely torture. It was horrible. Forty-five minutes. Maybe 30 degrees in there and then the altitude would get set to somewhere in Argentina or Chile where the mountains are. You're just coming out dripping in sweat."

The road back was not a straightforward one. Souttar underwent four separate operations during his recovery and admitted there were days when motivation was difficult to find. "Obviously you have good and bad days," he said.

"Some days you go in and, being honest, you can't really be bothered to do anything. But there are days that you just go head down and get through the work because you know you're working towards a goal. My goal was to get back in the squad."

That resilience is nothing new. Souttar had already recovered from a serious ACL injury earlier in his career and has shown exactly the sort of character that Chris Wilder is desperate to surround himself with to get back on the pitch.

He did that towards the back end of the season with City and has played in both Australia’s World Cup games so far. The next is Friday, against Paraguay and in many respects, this World Cup is less an audition of Souttar's footballing ability than of his durability. More than a few at United may be keeping half an eye on how it unfolds.