BROOKLINE, Mass. — The 122nd U.S. Open represents a massive week for Rory McIlroy.

For one, he’s entering Brookline as the favorite. He’s played some of the best golf in the world over the last several months, and he arrived at The Country Club fresh off his 21st PGA Tour victory. Every major week is a big one for a man looking to end an eight-year drought, but when you’re in form like he is, the pressure ramps up even more.

And, oh yeah, there’s also that (not so) little elephant in the room that is LIV Golf. The Saudi-backed league represents an existential threat to the order of professional golf, and with every passing week and big-name commit, LIV becomes more menacing. One week after LIV’s inaugural event, the rift between the establishment and the start-up has never been more glaring.

McIlroy has long been one of the most outspoken critics of the league, and he’s remained steadfast in his loyalty to those in Ponte Vedra. No one wants to preserve the integrity of the PGA Tour more than McIlroy. He secured a statement win north of the border last week — a day after LIV wrapped its inaugural tournament — but that was just another event. This is the U.S. Open. A win here would have a different gravitas in the fight for the soul of pro golf.

Eighteen holes in, and a statement win is well within reach. After a four-birdie, one-bogey round of 67, McIlroy finished the morning wave tied for the lead at three under. If he can put together three more rounds like that, Team PGA Tour will have scored a haymaker in its bout with LIV.

Ask McIlroy, though, and he won’t admit as much. On the course, it’s just golf. Making a statement with his clubs isn’t on his mind.

“It’s been eight years since I won a major,” he said, when asked if what’s going on in the golf world motivates him. “I just want to get my hands on one again.”

But for the objective observer, it was impossible not to notice some dissonance between McIlroy’s behavior on the course Thursday and his post-round comments. There was a certain edge to McIlroy between the ropes at The Country Club on Thursday morning — and he wasn’t shy about showing it.

Take the 5th hole, for example. McIlroy played his opening nine holes in two under, and that’s where he sat when he arrived at the tee box of the drivable par-4. After a long wait on the box, McIlroy’s drive leaked toward the bunkers right of the fairway. But instead of gravity pulling the ball into the deep bunker, a thick tuft of rough suspended the ball over the lip.

When McIlroy saw where his ball had settled, he wasn’t pleased. (“F—!” he said.) With the ball well above his feet, he lashed at it and sent it careening into another bunker some 10 yards closer to the green. He continued to vent his frustrations by taking a few lashes at the sand, sending sediment flying into the air.

“It’s one of those things it happens here, it doesn’t really happen anywhere else,” he said. “You just have to accept it. I gave the sand a couple of whacks because I’d already messed it up, so it wasn’t like it was much more work for [caddie] Harry.”

McIlroy ended his adventure at the 5th by rolling in a 10-footer for par to keep his card blemish-free.

“I just reset and played a decent bunker shot,” he said. “It was really nice to hole that putt.”

The gettable 7th hole represented another reminder about what this week holds. When McIlroy’s 30-footer for birdie dropped into the cup, he let out a small fist pump and raised his putter to the sky. As the roars died down, a fan in the bleachers adjacent to the green started a chant.

“PGA! PGA!”

Whether or not McIlroy wants to admit it, this week means more than major championship glory. The battle for pro golf is on, and he’s on the front lines.

Luckily, his play is backing it up.

Golf.com Editor

Zephyr Melton is an assistant editor for GOLF.com where he spends his days blogging, producing and editing. Prior to joining the team at GOLF.com, he attended the University of Texas followed by stops with Team USA, the Green Bay Packers and the PGA Tour. He assists on all things instruction and covers amateur and women’s golf.