Despite being 36 years old and facing constant questions about his retirement, Federer has continued to remain at the top of the game.
The current world No 2 is on course to battle for his 20th Grand Slam title and has not yet dropped a set in the Australian Open.
Federer is the reigning champion at Melbourne having beaten Rafael Nadal in a thrilling five-setter last year.
He faces Marton Fucsovics today for a place in the quarter-final where he will face either Tomas Berdych or Fabio Fognini.
And Novak Djokovic’s coach believes Federer is far from finished in the game.
“Listen, I’m out of the business of predicting him any more because I’ve been wrong so many times,” Agassi said.
“He keeps impressing and the game should just love him and appreciate him while he’s here.”
“He manages himself really well. He makes a lot of great decisions.
“The only thing I can say in full confidence is that when the end comes, it does come quick. But that doesn’t mean he’s at the end.
“He’s obviously made some very calculated, smart decisions to get his body to what it needs to be to able to keep doing this.
“So it wouldn’t surprise me for him to be around for a while longer.”