The former Chelsea star was offered the coveted No7, but instead took Anderson's No8.
"Many of you are asking me about the number 8 on my shirt," he wrote in his blog.
"I think it's a nice and important number, and I hope it brings me luck!
"What a coincidence: this is the eighth day since I signed with United. Very intense days, and very emotional as well.
"It's not easy to assimilate all this in such a short period, but it becomes easier with your help. The truth is I feel very comfortable on the pitch with my team mates. More and more after every game "
For breaking stories and all the great banter like us on Facebook: facebook.com/tribalfootball