sentences:  United were denied a goal when a header from Nemanja Vidić crossed the line before being cleared by Pedro Mendes.Portsmouth were under the cosh for most of the game but hung on until Wayne Rooney came off the bench on the hour mark.Rooney tapped in a cross from Ryan Giggs to break the 0–0 deadlock, before doubling United's lead with an audacious chip over the head of David James.