Manchester United lost 4-2 against Ruben Amorim’s Milan in their final pre-season friendly, after Bruno Fernandes missed a penalty for the second match in a row and they conceded three goals in the space of 14 minutes in the second half.Michael Carrick’s team took the lead in Wroclaw, Poland, after only two minutes, when Harry Maguire scored a header from a Fernandes corner. Milan hit back on 37 minutes when an unmarked Samuel Chukwueze slid the ball into the net after being found by their new signing Goncalo Ramos.Then, shortly before the break, Fernandes had a penalty saved by the Milan goalkeeper Lorenzo Torriani, three days after he missed in a penalty shootout against Leeds United.In the second half, Patrick Dorgu restored the advantage but Carrick’s side lost control of the game and Milan earned their first win under the former United manager Amorim thanks to goals from Alphadjo Cisse, Ramos and Ruben Loftus-Cheek.Laurie Whitwell analyses the key talking points from United’s defeat at the Wroclaw Stadium…Where did it go wrong for United against Milan?United’s defensive vulnerabilities were exposed by Milan in the second half as Amorim’s team scored three goals in 14 minutes to turn the result on its head.The ease with which Milan opened up United, each time down the right flank, was alarming, even with this being a game where players were getting fitness back and substitutions were made.Milan’s equaliser to level the score at 2-2 came when Chukwueze ran unimpeded into the box, with Luke Shaw backing off, then hit a pass through a crowd for Cisse to tap in at the far post. Cisse looked offside but he was allowed too much space regardless.United defenders appeal for offside as Cisse celebrates (Sergei GAPON / AFP via Getty Images)Carrick then made six substitutions, with Argentina international Lisandro Martinez making his first appearance of pre-season on the left side of central defence.That was the area of the pitch from which Milan went ahead, with Chukwueze again allowed time to pick his cross, which Ramos headed in after finding space with some smart movement.Milan’s final goal had a comical air to it, Loftus-Cheek sprinting away from Martinez and then picking his spot past the United goalkeeper Senne Lammens at the near post.This was a first match back for Kobbie Mainoo and Rashford too, and that will be a factor in Carrick’s line-up for the Premier League trip to Hull City next weekend. But they will need to defend better than this when the real action starts.Should United be worried by Fernandes’ missed penalties?These are only friendlies, but it is notable Fernandes has missed two penalties in successive games for United.