Manchester United's early season problems were compounded by a humiliating 4-0 loss to third-tier Milton Keynes Dons in the League Cup second round leaving new manager Louis van Gaal still looking for his first win.
MK Dons' Will Grigg and substitute Benik Afobe scored two goals apiece as United's defensive frailties were ruthlessly exposed by their enthusiastic lower division opponents who took advantage of playing against a second-string side.
Grigg capitalised on United's mistakes to score either side of halftime before Afobe compounded the visitors' misery with two late goals, the first seconds after coming off the bench.
Dutchman Van Gaal is still without a competitive victory since taking over at United in the close season and he will be desperate for British record signing Angel Di Maria to play after he signed from Real Madrid earlier on Tuesday.
"It's a matter of making errors at wrong moments," Van Gaal told Sky Sports. "When you see the goals against us, I believe they were big errors that you cannot make.
"Then it was 2-0 and it was very difficult to come back into the game. In the second half we created a lot of chances and didn't have the luck to score. Then two more errors and it's 3-0 and 4-0."
It was United's first outing in the second round of the competition since 1995 and the first time they had conceded four goals in a League Cup match against lower league opposition.
Elsewhere, West Ham United lost 5-4 on penalties at home to Sheffield United following a 1-1 draw after extra time, while fellow top-flight sides Leicester City and Burnley went down 1-0 to visiting Shrewsbury Town and Sheffield Wednesday respectively.
Dwight Gayle scored a first-half hat-trick as Premier League crisis club Crystal Palace, without a manager after Tony Pulis left the club, enjoyed a 3-0 win at third-tier Walsall.
Newcastle United won 1-0 at Gillingham, Southampton beat Millwall 2-0 away, Swansea triumphed 1-0 at home to Rotherham United and West Bromwich Albion beat visitors Oxford United 7-6 on penalties with the teams locked at 1-1 after extra time.