Sir Alex Ferguson’s dream of claiming the second treble of his illustrious career ended disastrously in his own backyard last week against Real Madrid.
Manchester United’s collapse at home to Chelsea on Sunday also dented their hopes of landing their first double in 14 years, too, highlighting the fact that there are some serious frailties at the heart of the Red Devils' back-line.
Nemanja Vidic and Rio Ferdinand’s influence has started to wane, whilst Patrice Evra is surely coming towards the end of his tenure in Manchester, too.
There are still several young, quality defensive players on United’s roster though, and Jonny Evans, Chris Smalling, Phil Jones and Rafael have each prospered thanks to prolonged periods in the team.
But you can’t help but feel that Ferguson is set to spruce up his defence this summer, by making a marquee signing in the mould of Jaap Stam in 1998 and Rio Ferdinand in 2002.
But who should make their way to Old Trafford? Here are five defenders they should target in the summer transfer window.