Shane Lowry was "annoyed and p***** off" for chipping himself into the Open shake-up and then putting his way out of it.
An emotional Lowry was crestfallen after he propelled himself into contention, basking in the high of back to back eagles from off the ninth and 10th greens, before making three bogeys on the way in before a closing birdie on 18.
"Yeah, it was a very emotional day," said the 35-year-old.
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"I felt like through the middle of the front nine I was just going along OK, not doing anything great.
"Obviously 9 and 10 happened and I felt like I was in the tournament - and did well to play my way out of the tournament from there.
"Pretty annoyed and pretty p****** off, to be honest.
"And I keep telling myself, and you keep saying all the time, that you want to get yourself to the back nine on a Saturday with an opportunity to do something great.
"And I got myself there today and I didn't perform. So that's very disappointing."
It is believed that Lowry's back to back eagles on par 4s in the open has never happened before.
And he was the first to make back-to-back eagles at the Open in 21 years, since Phil Mickelson did it at Royal Lytham.
The massive galleries gathered around the turn roared their approval as Lowry rocketed into the top five on the leaderboard as the leaders were teeing off.
"Hit a poor tee shot on 9 and got a pretty good break and just hit a lovely pitch," recalled Lowry.
"It was a nice lie in the rough and I could be fairly aggressive. I knew it was going to spin and hit a lovely shot.
"And 10, I hit a great drive and had a straightforward enough pitch. But it was a tricky pin.
"I was just trying to get as close as I could, and it just came out perfect and went in. Like the putt there, it was pretty cool, and it was good fun when those two went in.
"But the rest of the day wasn't so enjoyable.
"Look, I feel like I played OK, but it wouldn't take Einstein to figure out what went wrong on the back nine. My putting was horrific.
"I'm so disappointed to be honest because I worked so hard, and I work so hard to get myself in those positions, and I'm as disappointed as I've been in a long time.
"To be honest, I wasn't going to come in here (to talk to the media), but it's just hard. You feel like you're there, like you've got a good chance.
"I shoot 1-under for the last seven holes and I'm very bullish about my chances going into tomorrow - but now I have no chance. It's just very disappointing."
The Clara man's momentum came unstuck at 12, when he three-putted from 15 feet after a booming drive down the right hand side that crept close to the green and a chip up that was just short of being perfect.
Fine margins are everything on the Old Course and it was there that Lowry's round unravelled.
"Hit a beautiful pitch there," sighed the 2019 champion. "To be honest, if that rolled another foot it was stiff and it was a birdie.
"But it didn't, it stayed on top. And I couldn't really stop the putt, knocked it six feet by, missed that one.
"And yeah, it was just from there on in, it just wasn't great. I played good, but I just didn't putt good enough.
"It's not good enough to give yourself those chances on the back nine of a major on a Saturday and Sunday and you don't perform. You need to look at something.
"Look, I'm going to go away, I'm going to have to go to the putting green this afternoon and try to figure out something for tomorrow because it hasn't been good enough all week.
"If I had holed anything all week I would still be out there playing. I'd be thereabouts with the leaders. It just ain't good enough."
Lowry is at least hopeful of a low round tomorrow to leave St Andrews in a more positive frame of mind.
"I'm playing good enough," he stressed. "My game has been good enough all week.
"To be honest, I think it's a credit to my game the way I fought to be top 20 going into Sunday around here.
"So, yeah, I'm fairly bullish about if I do figure something out, I could shoot a score tomorrow. But I'm trying my best. Like, I don't have the answer.
"If I did, I wouldn't need to go to the putting green now. But it's just hard. This game is hard sometimes."
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