United was brilliant in the first half, as impressive as it has been in the 12 months of its Norwegian manager's tenure, and a penalty from Marcus Rashford followed by Anthony Martial's sharp finish made it the Red Devils' day. A late Nicolas Otamendi header could not save the host.
City sits 14 points behind Liverpool in the Premier League, hopes of defending its title surely all but extinguished by this result. Questions will be asked of Pep Guardiola's leadership, and how he has allowed the defence to become such a weakness.