Luke Shaw's nightmare injury is set to completely change the dynamics of the Manchester United squad under the Louis van Gaal regime.
Ultimately, after changing his back four - and five - time-and-time again throughout the course of last season, the Red Devils chief finally found a settled defence in Manchester.
The back-four of Matteo Darmian, Chris Smalling, Daley Blind and Shaw had enjoyed a fine start to the campaign.
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Now, though, Van Gaal has to change things. Shaw won't be available for some time, so who will replace him over the coming months? The smart money would go on either of Marcos Rojo or Daley Blind.
Rojo, an established Argentine international, would slot nicely into the back four, which would keep Blind alongside Smalling at the heart of the club's defence. However, Rojo's preferred position is at centre-back, so the United chief has the option to move Blind to the left while giving Smalling a new centre-back partner at the Theatre of Dreams.
Selecting Rojo or Blind would be the easy option, but Van Gaal may well have another trick up his sleeve.
In his press conference ahead of this weekend's game with Southampton, the enigmatic Dutch coach mentioned Ashley Young when discussing candidates to replace Shaw.
Despite being recognised by many as a winger, Van Gaal admires the England international's defensive traits. Last term, as Shaw struggled to prove his credentials, Young featured at wing-back for the club.
As United prepare to take on the Saints tomorrow afternoon, Young may well be gearing up for another stint at the back.
Handing the former Aston Villa man a role in defence would no doubt come as a surprise to the Manchester United faithful, but it could work. In Darmian and Shaw, United have had two flying full-backs, who have been prepared to roam forward in each game.
Young is comfortably one of the fittest players at the club, so could offer the team a great deal down the left-flank. Memphis Depay, who continues to prove his class in Europe, is yet to really hit it off in the Premier League, but would no doubt enjoy forming a relationship with Young out wide.
There's no reason why the duo won't be able to cause all sorts of problems to their rivals when on the attack. You never quite know what you're going to get from Van Gaal, so this decision wouldn't prove as strange as it may first appear.
Manchester United fans: Who should replace Shaw? Have your say below!