McIlroy, the No. 1 player in the world and defending champion at the Honda Classic, caused a stir Friday when he walked off the course after eight holes at PGA National when he was 7 over for the second round. He told reporters he was "not in a good place mentally," and an hour later issued a statement attributing his withdrawal to a sore wisdom tooth.
He signed with Nike during the offseason. In three starts this year, McIlroy has missed the cut, lost in the opening round of the Match Play Championship and withdrew from the Honda Classic after 26 holes.
"Rory is so talented," Nicklaus said during a visit to the NBC Sports booth at the Honda Classic. "He's a good kid. I think he's a little frustrated, and he's frustrated at himself right now. He's probably not playing his best, and he also has a set of golf clubs that he's having trouble getting used to, and one sort of plays off the other. He'll be fine. When Augusta rolls around, he'll be fine."
McIlroy is expected to discuss his withdrawal from the Honda Classic at a Tuesday news conference ahead of the WGC-Cadillac Championship, according to reports.
McIlroy plays out of The Bear's Club, which Nicklaus built as his home club for South Florida. The 23-year-old from Northern Ireland seeks advice from Nicklaus whenever he sees him. According to a report from IrishGolfDesk.com, McIlroy has been working with his swing coach there since withdrawing. Nicklaus said he last spoke to McIlroy last Monday.
"He was struggling a little bit with his irons," Nicklaus said. "But he felt confident of it. I said, 'Don't worry about it. You're too good of a player. Your clubs will not make that much difference.' Maybe it's easy for me to say."
Nicklaus said he once played three different sets of clubs depending on whether he was in America, Britain or Australia. He played in an era when a smaller golf ball was used specifically for the Open Championship, which he won three times and was runner-up seven times.
"I was able to go back and forth, back and forth. It wasn't that big of a deal," Nicklaus said. "Maybe the guys today, maybe they're so used to having one thing. I always feel like it's your talent that plays, not the golf club."
McIlroy had said at the start of the week that his swing was more of a problem than his new clubs.
Johnny Miller, the NBC analyst and two-time major champion, said McIlroy should not have walked off the course in the middle of the round.
"John, if he had waited five more minutes he wouldn't have done that," Nicklaus replied. "I think he's a good kid. He tries to do the right thing. Unfortunately, that probably wasn't that time."
Information from The Associated Press was used in this report.