straight to your inbox every day for freeManchester United assistant manager Mike Phelan has sent a message to Kai Rooney upon his signing for the Reds. Kai is the son of United great Wayne Rooney, who starred for the club from 2004 to 2017.Rooney's son may only be 11 years of age but he is already on the books at United after signing this week, with the former England international sharing a picture on Twitter of himself with Kai and his wife Coleen at Old Trafford."Proud day.