While Ferdinand has been at the top since a teenager, Williams worked at a fairground, a bowling alley and in a restaurant during a spell in non-league.
Now the unlikely pals go head-to-head when Manchester United face Swansea tonight.
Swans defender Williams said: "Rio and me have the same agent.
"I first met him through the agency and it developed from there. We all went away together in the summer and got to know each other.
"We don't actually speak too much about football.
"He's a cool, funny guy but quite normal. I am looking forward to playing against him.
"There will be no banter until after the game though.
"I'll probably message him and see how he's getting on in his Twitter argument with Sepp Blatter."