Fourth-tier Grimsby Town pulled a shocking run of results, eliminating Manchester United from the Carabao Cup.
The historic upset was decided on penalties after both sides ended in a 2-2 draw in regular and extra time of the clash.
Errors from goalkeeper Andre Onana gave the host a 2-0 lead before new signing Mbeumo and Maguire equalized late in the second half.
Bukayo Saka set to miss up to four weeks after hamstring injury
Arsenal working to sign Bayer Leverkusen defender Piero Hincapie
During the penalty shootout, both Cunha and Mbeumo had their penalties denied, ending 12-11 in favour of Grimsby Town.
The results have piled pressure on manager Ruben Amorim as to whether he will turn things around and bring Manchester United back to its glory days.
Amorim has been accused of using a failing formation and forcing players to play uncomfortable positions, thus failing to deliver.
