Rory McIlroy labelled himself "brain dead" and "unconscious" after slumping to a first round of 79 in the Open Championship at Muirfield.
McIlroy won five times in 2012, including a second major title by eight shots in the US PGA Championship, but has posted just one top-five finish in 2013 since his controversial multi-million pound switch to Nike in January.
The 24-year-old confessed to feeling "a little lost" as he missed the cut in the Irish Open last month and again cut a downcast figure after he completed the back nine in 42, including putting off the 15th green into a bunker.
"I don't know what you can do," the world number two said. "You've just got to try and play your way out of it. But it's nothing to do with technique. It's all mental out there. And then I just need to concentrate, obviously.
"But sometimes I feel like I'm walking around out there and I'm unconscious. I just need to try to think more. I'm trying to focus and trying to concentrate. But 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."
McIlroy walked off the course midway through the second round of his defence of the Honda Classic in March saying he was not in the "right place mentally" and threw one club in frustration and leant on another so hard that he bent the shaft out of shape in the final round of the US Open last month.
After missing the cut in the Irish Open, McIlroy spent time in London testing more Nike drivers and insisted he had found the right one, but other parts of his game remain well below par.
"I felt like I had made a lot of progress but then you shoot a round like this and you go back to the drawing board. I'm definitely under-thinking on the golf course, maybe over-thinking it off of it.
"I feel like I got off to a decent start, made a couple of silly mental errors on the fourth and fifth, a good two on seven and had a chance to get back to even par on nine. The start of the back nine was not very good."
Bogeys at the 10th and 11th were followed by a double-bogey six at the 12th, McIlroy adding: "Going left of the pin on 12, when I had no right to be going anywhere near that pin, that's just thoughtless. It's just so brain dead.
"Seriously, I feel like I've been walking around out there like that for the last couple of months. I'm trying to get out of it. I just don't quite know why."
A birdie on the 13th repaired some of the damage but the Northern Irishman then putted off the 15th green into a bunker and ran up his second double bogey in the space of four holes.
McIlroy admitted he was suffering from a lack of confidence and could go back to working with a sports psychologist.
"I've worked with Bob (Rotella) before a little bit. It could be beneficial to see someone like that again, we'll see," he added.
"I felt like I struck the ball okay. So as long as I can somewhat get my mind in a better place, I can go out there and try and shoot a good score tomorrow.
"I want to try to be here for the weekend. But the thing that I need to do tomorrow is just go out there and freewheel it and try and make birdies and try and play with that little bit of whatever it is I have usually. That's what I've to try and go out and do tomorrow, even though it's going to be tough to make birdies out there obviously."