Rory McIlroy is one of a tiny group of players who could be considered the best golfer in the world. Someone might want to remind him of that.

“Sometimes I feel like I’m walking around out there, and I’m unconscious,” McIlroy said Thursday in the moments after his first round of the British Open. “I just need to try to think more. I’m trying to focus and trying to concentrate. But yeah, I can’t really fathom it at the minute, and it’s hard to stand up here and tell you guys what’s really wrong.”

Thus, McIlroy’s vein opened, and his blood flowed following his miserable Muirfield experience, an opening 79 that featured three three-putts, one putt off a green and into a bunker, two double bogeys, and countless puffed-out, exhaled cheeks joining sadly slumping shoulders. With that, the world’s No. 2 player — winner of the PGA Championship last summer — must contend not for the Claret Jug, but for the right to play the weekend.

“It’s nothing to do with technique,” McIlroy said. “It’s all mental out there.”

Take his putt at the par-4 15th, from just off the green. The putting surfaces at Muirfield are exceptionally quick given the dry conditions, but McIlroy’s strike raced across the green, blew by the hole, and tumbled into a bunker. Afterward, he didn’t blame the speeds of the greens, the length of the rough, the pin positions. He blamed himself.

“That’s just thoughtless,” he said. “It’s just so brain-dead. Seriously, I feel like I’ve been walking around out there like that for the last couple months. I’m trying to get out of it. I just don’t quite know why.”

McIlroy’s unexpected struggles have been well-documented. Because of the way he closed last season — winning the PGA, his second major, and then three other tournaments the rest of the year — much was expected of him this year. But now, after a switch to Nike clubs, he is 0 for 2013.

Thursday, he seemed to chase his round. When he missed a six-footer for birdie at 3, he followed with a three-putt bogey at 4, then an inexcusable bogey of the par-5 fifth. When he failed to get back to even par by birdieing the par-5 ninth, he reacted with a bogey-bogey-double bogey start to the back side.

“We’ve all been there where you make a bogey or so, and you just want to try to get that birdie back,” said Phil Mickelson, one of McIlroy’s playing partners. “And sometimes, in trying to get it back, you put it in a spot that you make another bogey. . . . He had a couple of shots that had a chance to get close to the hole and they ended up in a really bad spot.”

Now, for McIlroy, there is only digging out. In one morning’s work, he has gone from marquee attraction to afterthought, alone with his thoughts. That appears to be a dangerous place for him because, by his own admission, his mind scrambled.

“It’s strange,” he said. “I wish I could stand up here and tell you guys what’s wrong or what I need to do to make it right, because I feel like I’ve got the shots. It’s just a matter of going through the right thought process to hit them, and that’s something that I obviously haven’t been doing recently.”