While the prospect of blasting a golf ball 300 yards in front of a packed gallery presents no fears for the Northern Irishman, the thought of pitching a baseball 20 yards was weighing on his mind.
The reigning US Open champion was invited to toss the first pitch at Tuesday's Major League Baseball game between the San Francisco Giants and Houston Astros.
During his practice round at the Olympic club on Tuesday, McIlroy tested out his arm by throwing a few golf balls on the fairways but was no clearer about what his strategy would be when he steps on the pitcher's mound.
"I definitely would rather get booed at a baseball game than on a golf course," he joked. "It will be the first experience for me.
"I don't know whether to play it conservatively and just lob it into his hand or go for the fast one. I'm not sure."
The Giants were planning to mark the occasion by giving all the spectators a bobblehead doll of McIlroy as a keepsake.
"I think it's maybe better looking than me, which is a good thing," McIlroy said.
Never one to turn down a sporting challenge, this will not be the first time McIlroy has tried his hand at a different sport in front of a huge crowd.
Earlier this year, he suddenly found himself trading shots with Maria Sharapova on a makeshift centre court at Madison Square Garden after going to watch his Danish girlfriend Caroline Wozniacki play an exhibition match.
While a lot of other top golfers shun the spotlight, the 23-year-old McIlroy is completely comfortable in the public eye even though the demands on his time have increased dramatically since his record-breaking win at last year's US Open.
"It's just finding a balance of everything, with getting enough practice, sponsor commitments, media ... having a life outside of what you do around golf," he said.
"It's something I still feel like I'm learning to do but I'm not complaining. I feel like I'm in a great place and I'm happy to be doing what I'm doing."
McIlroy goes into this week's Open with real hopes of winning after an up and down year in which he briefly held the number one ranking after winning the Honda Classic and contested in a number of other events.
Not everything has gone according to plan and he missed the cut at two successive events last month but McIlroy is still carrying the confidence from his victory from a year ago.
"Hopefully it didn't change me much as a person. I still feel like the same person who sat here or sat at Congressional a year ago," he said.
"But in golfing terms I feel like it's changed me a lot. I feel like it's given me a lot of confidence. And I feel like I have a chance in these tournaments every time I tee it up."