Juventus midfielder Arturo Vidal is Manchester United's top midfield target but the club's concerns about his fitness are so great that it may require a complex, appearance-based contract if he is to follow Angel Di Maria into Louis van Gaal's squad.
After a summer in which United have persistently felt that Juventus have been seeking to manufacture a market for the Chilean – with a £34m asking price they have always considered too high – the desperate need for midfield protection has led to a softening of their tone.
But the player's troublesome right knee is a cause of serious concern, with United acutely aware that the 27-year-old has not started a Serie A game for the Turin side since the 2-0 defeat at Napoli on 30 March.
The player also played four games before the knee was operated on as Juventus needed Vidal as they fought to win last season's title and to progress into the Europa League.
The player underwent a rapid – some felt hasty – operation in May to repair his meniscus before the World Cup and was obviously never fully fit in Brazil, where he could not complete any of the three games he played.
Universidad de Chile's team doctor, Alejandro Orizola, described the operation that patched him up for the World Cup as "a hasty procedure" and claimed that "it would always bring with it a regression".
The substantial concerns about the injury could feasibly lead United to seek a highly-incentivised appearance based contract. It seems unlikely that United would be willing to pay anywhere near the asking price for a player who represents such a physical risk.
Despite the doubts, Vidal was name-checked twice by Van Gaal in his post-match press conference at Sunderland.
United would certainly want to put him through the most vigorous medical at the Carrington training facility – which is equipped with the technology to predict the likelihood of a player breaking down.
The indication from Old Trafford – where Di Maria is expected to be announced as a United player for a fee of around £60m today – is that Milan's Nigel De Jong will not be joining the club.
If Van Gaal is to be reunited with the former Manchester City enforcer, who was a part of his World Cup squad, he will clearly have to overturn the club's decision.
De Jong's absence from the Milan team for the weekend's Italian pre-season TIM Trophy has been seen as an indicator that the Dutchman may be on his way.
De Jong's desire to return to the Premier League to play for his former Netherlands manager means that Van Gaal knows it would be an easy deal to do.
An 11th hour move for Ajax defender Daley Blind, also from his Dutch squad, is thought be achievable for the same reasons.
Vidal is thought to be willing to leave Italy. Juventus' apparent willingness to sell Vidal all summer has demonstrated the changed environment for the player, who was previous manager Antonio Conte's main man and whose attachment to the club has weakened with the arrival of Massimiliano Allegri.
Another available midfielder, Real Madrid's Xabi Alonso, is of no interest to United, despite suggestions to the contrary in Spain – where his future looks uncertain after the arrival of Toni Kroos. Suggestions of Sami Khedira's departure for United are also wide of the mark.
United hope to register Di Maria by Friday so he is available at the weekend.