By Tom Gott Alejandro Garnacho has admitted the Manchester United squad were left seething after the controversial nature of Brentford’s goal on Saturday. The Red Devils were made to play with ten men temporarily as centre-back Matthijs de Ligt was forced off the field to deal with a head injury which left him with blood pouring down the side of his face. Without a key presence in the box, United fell 1-0 behind when Ethan Pinnock headed home from a corner late in the first half. Erik ten Hag admitted after the game that United channelled that frustration to produce a sensational second-half d…