Honorary starters Nicklaus, Gary Player and Tom Watson have all backed the Northern Irishman to triumph, after getting the 89th Masters under way earlier on Thursday.
World No.1 Scottie Scheffler is eyeing a third title in four years as he aims to become just the fourth back-to-back winner.
But world No.2 McIlroy is the sentimental favourite in hot form, chasing a career grand slam that's been in the reckoning since he won his fourth major in 2014.
Player revealed on Thursday that McIlroy had sought out Nicklaus for advice on how to end his agonising, 11-year wait for another major.
"I think it's about time that Rory won and I sat down with him last week," six-time champion Nicklaus, 85, said.
"I said, 'I know you prepared for Augusta, tell me how you're going to play the golf course'.
"We went through it shot-for-shot, we got done with the round, I didn't open my mouth and I said 'I wouldn't change a thing'.
"That's exactly the way I would try to play the golf course.
"The discipline to do that is what Rory has lacked in my opinion. He's got all the shots, he's got all the game.
"He certainly is as talented as anybody in the game, but if you go back through his history in the last few years he gets to a place and all of a sudden a seven or an eight pops up and that keeps him from getting where he needs to go."
Watson, Player and Nicklaus boast 11 Masters titles between them and were in fine form after their early-morning tee offs.
"I just have a gut feeling that Rory is the guy that's going to win this week. That's the bottom line. That's my gut feeling," Watson said.
South African Player said a McIlroy win would "give golf a great boost".
"He's the fittest golfer. He does a dead lift of 400 pounds (180kg). I don't know if you're aware of what a dead lift is," he said.
"Four hundred pounds ... if you do 100 pounds, it's exceptional.
"He went to Jack for advice on how to play this golf course.
"Nobody knows better than Jack. And I think timing in life, he's had his adversities, his opportunities to win majors and let them slip. I think his time is right."
The trio addressed the drawn-out merging efforts of LIV Golf and PGA Tour, nearly two years since a framework agreement was tabled.
Twelve LIV Golfers, including Australian Cameron Smith, are in the field this week.
"They made their choice to play their own tour, and that's where they are right now," Watson said.
"I don't see a real working mechanism for the two tours to get back together."
Nicklaus said he'd like to see the parties come together but made his stance clear in a swipe of sorts at 52-year-old Phil Mickelson.
"The PGA Tour is the tour, and that's where most of your good players are, and I think it's very healthy no matter which way it goes," he said.
"I don't know what level Phil is competing at. I guess he's still playing. He's playing the LIV Tour, is he?
"I don't know if he's playing or not. I don't know, you never see that anymore."
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