Butch Harmon has seen this before: A top player falling so in love with the gym that his golf game suffers.

Harmon saw that with Tiger Woods, and now he thinks he's seeing it again with world No. 1 Rory McIlroy.

"If you look at Tiger and how much stronger he got as he went on, you look at Rory the way he is now," Harmon said on the Irish radio program "Off the Ball."

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"The only caution I would give Rory is, I see a lot of pictures of him lifting a lot of very heavy weights and I think, in a way, you can almost hurt yourself in the gym if you get too bulky. Hopefully, he will keep his body tone down, more like a Dustin Johnson (a Harmon client), who’s in absolutely perfect physical shape to play golf."

McIlroy, with the help of sponsor Nike, posted a video this week of the four-time major winner's workout routine. In it, McIlroy talked about how he became dedicated to work in the gym, including using a workout as a reward for a good round on the course.

Harmon doesn't dismiss strength-training. However, Harmon, believes that training should focus on core strength -- particularly for someone like McIlroy who hits the ball so far.

He said, "That helps support your back and your back is not geared for making a golf swing thousands and thousands of times and you have to have the strength in your core to handle that."

Ryan Ballengee is a Yahoo Sports contributor. Find him on Facebook and Twitter.

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