Ruben Amorim has vowed to be Manchester United’s smiling assassin. The new United manager insists he's Mr Nice Guy when he’s winning - but the 39-year-old Portuguese has warned the club’s stars that there will be no hiding place in the Old Trafford dressing room if they continue to under-perform. Amorim evoked memories of Jose Mourinho telling the world that he was the Special One when he arrived at Chelsea in 2005 by describing himself as the Smiling One. But the former Sporting Lisbon coach