There's no doubt that the horrific season-ending injury to 20-year-old left-back Luke Shaw has given Manchester United more defensive problems in recent weeks than it seemed were possible.
Since Shaw broke his leg Louis van Gaal has been chopping and changing his defence, even resorting to the likes of Antonio Valencia and Ashley Young as emergency defenders.
Not only were they not compact at times in the nervy win over Wolfsburg but they were also ripped apart with ease by Arsenal in the opening 20 minutes on Sunday in a messy, scrappy, abject defensive display.
In the wake of the poor first-half performance against Arsenal, this article suggests Man United's best back-four based on the players who will be available for selection after the international break.
RIGHT-BACK - MATTEO DARMIAN
Matteo Darmian looked ragged at the Emirates Stadium and quite frankly couldn't cope with the movement, trickery and guile of Alexis Sanchez. The 25-year-old Italian appeared worryingly inept on Sunday however he has probably been Man United's most consistent summer signing.
He defends well in one-on-one situations, provides good energy up and down the right flank and his reading of the game is exceptional. With the exception of the Arsenal game Darmian has looked solid and secure at both right-back and left-back and he's proved that he knows how to defend properly.
CENTRE-BACK - CHRIS SMALLING
English centre-half Chris Smalling has become the undoubted leader of Manchester United's defence over the past 12 to 18 months and so far this season he has performed consistently at his dominant best.
Smalling is now an aggressor who looks to impose himself on opposition forwards and has even captained United under Van Gaal. He's strong, quick, powerful and at just 25 years of age he's quickly becoming one of the first names on his manager's teamsheet.
CENTRE-BACK - PHIL JONES
Dutchman Daley Blind has played more minutes for Manchester United this season than any other player and the technical quality he now provides from a deeper position has been priceless for United on many occasions over the past few months. Unfortunately for Blind teams are now starting to isolate him in games which is exposing his lack of pace and power.
Phil Jones is taller, stronger and much less likely to be bullied by opposition strikers than Blind. Many perceive the 23-year-old Englishman to be a clumsy customer but in reality Jones is a very good defender who snuffs out dangerous attacks and never hesitates to put his body on the line with last-ditch blocks and tackles.
LEFT-BACK - MARCOS ROJO
Marcos Rojo isn't a natural left-back, but he's played there many times for Argentina, including last year's World Cup final, so he knows what he's doing.
He makes lots of interceptions and clearances, he covers his centre-backs well and he loves to get forward too. Rojo, like Smalling, is quick, but he's also very good on the ball and he has the ability to make things happen wherever he is on the pitch.
He's struggled to get fully fit following the Copa America this summer but after the shocking first 20 minutes at Arsenal Rojo has surely got to be a better option at left-back than winger Ashley Young.
Ever since Chris Smalling and Phil Jones moved to Old Trafford as youngsters they have been touted as being a potential top-class central defensive pairing for both United and England. Rio Ferdinand, Nemanja Vidic and Jonny Evans have all left the club in recent years so now is the time for the duo to step up and take on more responsibility.
The added security of wily, assured defenders Darmian and Rojo alongside Smalling and Jones could help United to regain their solidity at the back, better protect David de Gea's goal and keep more clean sheets going forward.