The two-time Masters champion, who collected his second green jacket four months ago at Augusta National, decided against taking part in a long-drive contest worked into practice rounds at the par-5 10th hole Tuesday, saying tournament preparation took top priority.
"I want to practice the game of golf. I want to learn this golf course," Watson said.
"I don't see that we should have a competition like that while we're playing a practice round and learning the golf course."
South African Louis Oosthuizen won the long-drive contest with a 340-yard effort, two yards longer than Australian runner-up Jason Day, while Watson used a 3-iron instead of a driver, taking himself out of contention to make his point.
And even though McIlroy led the driving statistics last week in winning the World Golf Championships event at Akron, Watson was not interested in talking about a ball-smashing contest in his grouping of major champions when he could contend for a major title.
"When we get here to the tournament Thursday, it's about playing a game," Watson said Tuesday. "He doesn't care if he outdrives me. I don't care if I outdrive him. We're trying to score.
"If I outdrive him every hole and he beats me, he doesn't care. If he outdrives me every hole and I beat him, it doesn't matter. It's a big field so we are not looking at each other."
World number one McIlroy, who won his third major title at July's British Open, averaged a PGA season-best 334 yards off the tee last week and ranked 12th in driving accuracy while leading in greens reached in regulation as well.
Watson says he is not shocked that the relatively diminutive McIlroy can smack the ball a long way.
"It doesn't surprise me at all. His technique is obviously pretty good," Watson said.
"He's number one in the world. He's still young. But no, I don't really think that it's the size. I think his technique is so good that obviously he can move the ball out there. It doesn't surprise me how tall somebody is if they can hit it pretty good. He's pretty strong, too. He's pretty fit."
Watson and McIlroy and US Open winner Martin Kaymer of Germany will play together in the first two rounds over a 7,458-yard, par-71 layout that features the 597-yard par-5 seventh and 590-yard par-5 10th plus three par-4s above 490 yards.
- Demanding greens -
"A big hitter that's hitting his driver well can play this course," Watson said. "The rough is not too demanding and the fairway. It's really demanding around the greens.
"If you can somehow hit a lot of greens, it doesn't have to be close, you will be able to score a little bit around here."
Watson selected to hit a 3-iron off the 10th tee rather than a driver to protest the insertion of the long-drive contest into the round, even if it was meant as a fun distraction for players.
"There's no reason to make something up in the middle of the practice round like that," Watson said. "This is just right there in the middle of your practice round when you're trying to see the course. Just kind of weird to me.
"But I hit my 3-iron perfect, though, right down the middle. Longest 3-iron of the day. I won that competition. Take that."
But during the tournament, count on seeing a driver in his hands on the 10th tee.
"It will be driver every day," he said.
Watson, known as a laid-back character, was surprised to hear he was being criticized for taking himself too seriously in his attitude over the long-drive event.
"I'm here to win a championship," he said. "I'm not here to goof around."