A plethora of high-profile attacking signings had expectant Manchester United fans dreaming of a return to the upper echelons of European football, but their failure to identify their defensive problems is threatening to derail those hopes.
Against newly-promoted Leicester City on Sunday, United's porous defense conceded five goals in an astonishing 5-3 defeat, twice squandering seemingly comfortable two goal advantages.
At times United's attacking quintet of Radamel Falcao, Robin van Persie, Wayne Rooney, Angel di Maria and Ander Herrera dazzled their opponents.
But as the old saying goes 'you're only as good as your weakest link' and United's is a defence bereft of, and utterly lacking the defensive resolve, organisation and concentration required to re-establish themselves as a footballing force.
‘I don't think it is the weakness of our defence’
This off-season saw the departures of club greats Rio Ferdinand, Nemanja Vidic and Patrice Evra, whose partnership was the foundation for a hugely successful period that yielded over 1,000 appearances and 30 trophies combined.
Against Leicester, United lined up with a back four of Marcos Rojo, Tyler Blackett, Jonny Evans, who went off injured, and Rafael but manager Louis van Gaal's believes it is the system rather than the personnel where his problem lies.
"I don't think it is the weakness of our defence, it is the weakness of our defensive organisation from the team. That we have to do better," van Gaal told Sky Sports.
"You have to know when you can pass the ball and when you have to get rid of the ball. In this game, at 3-1 I felt we had played fantastic football but then you cannot make the errors we did.
"You cannot say the defence was weak," he later told the BBC. "You play like a team, Leicester showed that, we did not play like a team in the second half and that is not only defence.
"In a defensive situation the whole team is responsible, not just one defender. We have too many players who want to seek for the goal."
United started the season with van Gaal adopting the 3-5-2 system which had worked so successfully as he guided the Netherlands to a third placed finish at this summer's World Cup.
They failed to win any of their first four games in all competitions at the start of this season and with the experiment deemed a failure, van Gaal reverted to a diamond formation.
That paid dividends with an emphatic 4-0 win against Queens Park Rangers last week which even prompted talk of the title or a top three finish in some quarters, but Nigel Pearson and his ever-impressive Leicester team exploited its limitations with ruthless efficiency.
‘It is not just about technical ability’
"When you play against the diamond, the players who are going to have the most time are both full-backs. But we were able to exploit areas down the side of the back four on the transitions," Pearson told the BBC.
"We didn't do it well enough for long periods in the first half but were better in the second. The players have to take credit for how they went about putting into practice what we talked about and also their resilience. It is not just about technical ability."
Jamie Vardy, man-of-the-match and scorer of Leicester's fourth goal, said: "We had done our research this week and their attacking options are frightening but the diamond formation they play leaves a lot of space behind the full-backs and we looked to exploit that."