The United star was in the front row enjoying the Monday Night RAW action as he was approached by Preston fan Barrett and goaded by the wrestler.
Rooney reacted angrily giving the Barrett a hard slap to the face shocking the Manchester crowd.
Barrett, the 2015 King of the Ring, was accompanying ally Sheamus to the ring for his match against Cesaro at the event.
Before the match he took to the mic and said: "In this ring are two men who can be easily be described as championship material.
"Which is, of course, more than can be said of Wayne Rooney and Manchester United.
"I would hate for your little boy to have to watch his own father fail. He gets to experience that every single time you step on a football pitch."
WWE are currently on a Europe-wide tour and will record their SmackDown show from Manchester on Tuesday evening.
OUT OF FORM: Some Man United fans have called for Rooney to be dropped
