Manchester United suffered one of the worst European nights in their history against Como to pile the pressure on beleaguered boss Michael Carrick.
Eight days after conceding in the first minute to Atletico Madrid, United's defences were breached after 118 seconds as brilliant Argentina playmaker Nico Paz scored the first of his double.
It meant United became the first English team in history to concede in the first two minutes of consecutive major European matches, something no-one at Old Trafford wants to be associated with.
When United last won the Champions League in 2008, Como were in Serie D. It is a measure of the different directions the respective clubs are heading in that this was about as comprehensive a victory and as one-sided a match as it is possible to imagine.
Paz scored twice, and set up Tasos Douvikas in between, before Jacobo Ramon powered home a header for number four.
At one stage it looked as if United may equal another unwanted record - their heaviest ever European defeat was a 5-0 loss to Portuguese side Sporting in 1964.
Skipper Bruno Fernandes was replaced by Joshua Zirkzee midway through the second half after Matheus Cunha and Andrey Santos - £110m-worth of Ineos signings - were taken off at half-time.
Zirkzee beat the offside trap to calmly score a consolation from fellow substitute Amad Diallo's cross in stoppage time, but that did nothing to improve the mood.