Nani was taken down on the left edge of the Chelsea penalty area, giving United a dangerous set piece opportunity. Wayne Rooney's free kick wasn't anything particularly amazing, but it was well placed at the far post and managed to find its way past several Chelsea player's heads and into the net.
Again Petr Cech looked extremely poor, getting himself in completely the wrong place as the ball was clearly going wide and he remained stuck in the center of the goal. It's possible he was expecting one of his defenders to head the ball away but by the time he finally reacted, it was too late.
What a start for United and unless Chelsea can turn things around quickly, the defending FA Cup champions look to be on their way out.