Rory McIlroy at US Open 2015: Friday Leaderboard Score and Twitter Reaction

In the space of two holes, Rory McIlroy went from potentially getting back to even par to four over for the 2015 U.S. Open, likely shutting the door on a second U.S. Open victory. 

The four-time major champion wrapped up his second second with another two-over 72, which dropped him into a tie for 44th at the time of writing. You can view an up-to-date leaderboard below:

McIlroy's score is particularly notable because the projected cut is five over. One more stroke the wrong way, and his U.S. Open would've been over before the weekend got underway.

Although the 26-year-old was flirting with the cut early in his round, an eagle on 12 and birdie on 15 looked to have provided enough just enough of a safety net. Then, he double-bogeyed 17 and bogeyed 18, undoing all of the progress he made from the earlier holes.

Kevin Van Valkenburg of ESPN thought the double-bogey signaled the end of McIlroy's title challenge:

Before the round, ESPN's John Buccigross highlighted how McIlroy's U.S. Open fortunes have taken a downward slide ever since he captured his first major title:

That trend continued Friday.

After Thursday's two-over 72 in the first round, McIlroy placed the blame for his struggles mostly on his putting, questioning the quality of the Chambers Bay greens as well.

"They are not the best I have putted on but I should be used to it as the last two tournaments I've played have been just as bad," he said, per Sky Sports. "I felt like I played well tee to green and gave myself a lot of looks but did not take advantage of the good shots I was hitting."

The good news for McIlroy is that his putting improved in Round 2 (1.89 putting average on Thurs., 1.72 putting average on Fri.), per USOpen.com; the rest of his game became the problem instead.

He only hit nine of his 14 fairways and made 11 of his 18 greens in regulation, both of which represented a decline from yesterday's numbers.

McIlroy started off Friday well enough, birdieing the opening hole. Bogeys on the third and seventh holes, however, put him at one over on the front nine. He responded with back-to-back pars on 10 and 11 before delivering the eagle on No. 12.

Golf Digest used that eagle to make a larger case about course layouts:

Following the 12th hole, McIlroy was slowly regaining his swagger and looking more sure of himself, which was a welcome development for Yahoo Sports' Jay Busbee:

The fun was only fleeting as McIlroy's bogey on 13 kicked off what would be an underwhelming finish to his round. As a result of his final two holes, he nearly made history Friday, per Golf Channel's Justin Ray:

It's not as if McIlroy was in serious contention at any point in this round. Even if he had stayed at one under for the tournament, he'd have still been six shots back of Jordan Spieth and Patrick Reed. His sluggish start to the U.S. Open really gave him a tough mountain to climb.

Still, at one over, there was the chance that McIlroy could have a brilliant third or fourth round and skyrocket up the leaderboard and become a serious threat.

Now, he has to make up nearly 10 shots in the space of two rounds. In other words, maybe McIlroy can pick up his fifth major at the Open Championship next month.