"I realized there was a penalty and I called an official over," Hayes said, according to the newspaper. "He said the penalty was two shots and that I had to finish the hole with that ball and then change back to the original ball."

Hayes shot a 74 Wednesday and a 71 on Thursday, putting him in good shape to finish in the top 20 and advance to the final qualifying stage in December.

But on Thursday night in his hotel room, Hayes realized that the errant golf ball might not have been on the approved list.

"It was a Titleist prototype, and somehow it had gotten into my bag," he said, according to the Journal Sentinel. "It had been four weeks since Titleist gave me some prototype balls and I tested them. I have no idea how or why it was still in there."

Hayes had a choice: He could have said nothing and kept playing, with no one aware of his mistake. Or he could turn himself in and let his mistake cost him a 2009 PGA Tour card.

He chose the latter.

J.P. Hayes, pictured earlier this year, accepted the consequences for using an unapproved golf ball during Q-school last week. David Matin/Getty Images

"I called an official in Houston that night and said, 'I think I may have a problem,'" Hayes said. "He said they'd call Titleist the next day. I pretty much knew at that point I was going to be disqualified."

As for his decision to turn himself in?

"I would say everybody out here [on the PGA Tour] would have done the same thing," Hayes said, according to the report.

Hayes, 43, is refusing to blame his caddie for the error, saying he should have spotted the errant ball because it did not have a model name on the seam.

"[The caddie] kind of wanted to take some of the blame, but he knows I'm anal about my equipment," Hayes said, according to the report. "I go through my bag every night. I want to know what's in there. It's almost therapeutic for me."

According to the report, Hayes said that if the hole had been a par-4 or a par-5, he would have known he had the wrong ball right away, because he uses the label to help him align his driver on tee shots.

"But it was a par-3 and I don't use the label to line up on par-3s," he said, according to the Journal Sentinel. "It was my mistake. I had no choice but to take my medicine."