Iconic former Manchester United manager Sir Alex Ferguson still terrifies one Red Devils legend who looked up to him and learned a lot from him. Sir Alex Ferguson, who is considered one of the best managers of all time, bowed out of Old Trafford in 2013 after an illustrious career at Manchester United. The 82-year-old Scotsman led United to a whopping 13 Premier League titles, with the Red Devils’ last league triumph coming at the end of the 2012-13 season. United were the first English team to complete a continental treble in the 1998-99 season, with Ferguson at the helm of the incredible fe…