It's a sad thing in football to watch a world-class star decay into inferiority, but this is unfortunately what has happened to Manchester United midfielder Casemiro. The Brazil international has won it all, anchored one of the most incredible midfield triumvirates in the modern game at Real Madrid, partnered with Toni Kroos and Luka Modric. Casemiro has been heralded as a "monster" by former Los Blancos boss Zinedine Zidane, while last season, at Old Trafford, Marcus Rashford hailed the tough-tackling titan as "essential" following triumph over Newcastle United in the Carabao Cup final.