Ferdinand arrived at United in a £30 million deal from Leeds and he was the world's most expensive defender at the time.
It'll come as no surprise that it didn't impress Keane though, who didn't allow Ferdinand to settle in at Carrington and criticised his safe style of play.
Ferdinand explained per Pundit Arena: "I got the ball and passed to Gary [Neville], who was on my team. In a normal game that was a great ball - pass to your teammate, go up the pitch.
"And then Keane turned around and just started going, 'Pass the f**king ball forward, take risks, you're not at Leeds or West Ham now, you're at Manchester United!'
"I got home later that day and thought, 'This guy is nuts, how am I going to deal with him on a daily basis?'"
Despite Keane's tough love, Ferdinand endured and he enjoyed 12 successful years with the Red Devils.
He won the Premier League six time as well as the Champions League in 2008, forming an incredible partnership with Nemanja Vidic.
The 42-year-old credits Keane's message with helping him improve on the pitch.
He added: "And then I realised that you've got to take chances and that's how I ended up playing my career. Not just passing the simple ball to Gary, but into the strikers to make a difference."
Keane did take aim at Ferdinand in his now-legendary MUTV rant after a 4-1 loss to Middlesbrough in 2005.
The Irishman missed that game through injury but unloaded on his teammates live on air.
Ferdinand said in his autobiography: "The reports said that Roy had been slamming a few of the young lads - Fletch [Darren Fletcher], Kieran Richardson, Sheasy [John O'Shea] and me. Apparently, he had questioned my right to my wages for that performance.
"The next morning when we came in, he told the manager he wanted to speak to us and play the tape. We were all in the changing room and he said 'Listen, I still wouldn't mind the tape going on air. I would have been happy for it to be played. The papers have made a meal out of what was said on the video. I never mentioned anyone's wages and I didn't insult anybody.
"I judged the performances honestly and if you are not criticising yourselves in the same way, then you shouldn't be at United.'
"It was just football analysis. I didn't have a problem with it."
Featured Image Credit: ITV Football & PA Images
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