The Italian side established a commanding four-goal advantage, with Argentina international Nico Paz playing a decisive role in the rout. Paz opened the scoring after just 118 seconds, continuing United’s alarming habit of conceding early in continental competition.
The Red Devils had also shipped a goal inside the first minute against Atletico Madrid eight days earlier.
That sequence made United the first English side to concede within the opening two minutes of consecutive major European fixtures, adding another unwanted distinction to their troubled campaign.
Como’s remarkable progress was also underlined by the result. When United last lifted the Champions League trophy in 2008, their opponents were competing in Serie D, the fourth tier of Italian football. The contrasting fortunes of the clubs were evident as Como dominated proceedings.
Paz doubled his tally and supplied the assist for Tasos Douvikas to extend the hosts’ advantage. Jacobo Ramon subsequently powered home a header to make it four, leaving United in danger of matching their heaviest European defeat, a 5-0 reverse against Sporting in 1964.
Carrick attempted to change the course of the contest by withdrawing Matheus Cunha and Andrey Santos at half-time. The pair represented a combined 110-million-pound investment by Ineos. United captain Bruno Fernandes was also taken off midway through the second half, with Joshua Zirkzee introduced in his place.
Zirkzee eventually found the net in stoppage time, racing beyond Como’s defensive line before finishing composedly from Amad Diallo’s cross.
Youri Tielemans admitted Manchester United were lacking in every department after their shocking 4-1 Champions League defeat to Como in Italy on Wednesday, which extended their winless run to seven matches.
Michael Carrick has admitted Manchester United's 4-1 defeat to Como was "not acceptable" after a disastrous Champions League performance on Wednesday, but insisted he was not worried about losing his job.
Paris St-Germain produced a thrilling performance to defeat Barcelona in the Champions League, ending the Spanish side's 11-match unbeaten start to the season with a 4-2 victory at the Parc des Princes.
Manchester City demolished AEK Athens 5-1 in a Champions League encounter at the Etihad Stadium on Tuesday night with Phil Foden sublime as he netted a hat-trick.
