Manchester United frontman Wayne Rooney has revealed that he has been struck down by an illness.

While there is no indication as to whether or not the complaint will keep him out of United's home encounter against Sunderland on Saturday afternoon, the 27-year-old was forced to cancel a book signing this afternoon.

"Not feeling good at all. Had to cancel the book signing today. Sorry to all the fans who were coming. I was really looking forward to it," he wrote on Twitter.

Rooney scored twice as United beat local rivals Manchester City 3-2 on Sunday at the Etihad Stadium.