Federer picked up his 20th Grand Slam title last month when he won the Australian Open at the expense of Marin Cilic.
The Swiss legend has enjoyed an illustrious career and dominated tennis for over a decade.
Rafter in the meantime, played Federer three times in his career and won all three of their encounters.
The Australian ran into the 36-year-old in the early stages of his career, and has pinpointed the moment when Federer transitioned from being a “soft” player to someone with a winning mentality.
“I think there were times early on when he showed me too much respect,” Rafter said.
“He was there in matches but kind of went away because he was too respectful.
“He was almost a bit soft. You could sense that change once he started to believe in himself.
“The last time when played (at 2001 Halle) a week before Wimbledon, you could tell things were changing.”
However, Rafter was quick to point out that Federer was not two-faced.
He added: “No, what you see in public is how he is.
“There are people in this universe who are just born a certain way and they behave a certain way.
“Good and bad. Roger’s a great bloke.
“I just wish I had something on him.”
Federer is hoping to use his wildcard to play in Dubai Open which gets underway on February 26.