Butch Harmon gave Newstalk's Off The Ball some juicy pre-Masters chat, covering the world No 1's love the gym, Tiger Woods and the form of clients Adam Scott, Dustin Johnson, Rickie Fowler and Jimmy Walker.
They will be some of McIlroy's biggest rivals at Augusta National but while Harmon is a little nervous that McIlroy might overdo the fitness regime, he's got no doubts whatsoever about the Holywood man's game.
"He's far and away the best player in the world," Harmon said. "We're only seeing the tip of the iceberg with Rory McIlroy. He can get so much better than he is right now."
As for Woods, Harmon said: "I have no desire to be his coach. Personally I don't think he needs a coach. I think he needs to go to the range and hit some shots, go back to playing golf."