Jesse Lingard was the villain for Manchester United as his poor backpass gave Young Boys a last-gasp winner to consign the Red Devils to defeat in their first Champions League game.
In front of a raucous atmosphere at the Wankdorf Stadium in Bern, Cristiano Ronaldo got United's evening off to the perfect start by netting his third goal in two matches since returning to the club, slotting home after Bruno Fernandes' exquisite cross.
But the game turned on its head when United's Aaron Wan-Bissaka received a straight red card for a high challenge on Young Boys' Christopher Martins.