PALM BEACH GARDENS, Fla. (AP) -- Rory McIlroy abruptly walked off the course Friday at the Honda Classic, telling reporters who followed him to his car he's "not in a good place mentally."
He later said it was more dental than mental, releasing a statement that he couldn't concentrate because of a sore wisdom tooth.
The surprising departure raised serious questions about golf's No. 1 player with the Masters just more than a month away. McIlroy has played only four rounds in three tournaments this year, and this was a clear sign of frustration.
McIlroy was asked three times if anything was wrong physically and said there was not.
"There's not really much I can say, guys," he told three reporters before he drove away. "I'm not in a good place mentally, you know."
McIlroy already was 7-over par through eight holes of the second round when he hit his second shot into the water on the par-5 18th at PGA National. He shook hands with Ernie Els and Mark Wilson and was headed to the parking lot before they even finished the hole.
Els also hit into the water on the 18th and was complaining to a rules official about the muddy conditions of the fairway when he realized McIlroy was through.
"I was dropping my ball and I realized he wasn't dropping his ball," Els said. "I thought maybe his ball crossed further up (the hazard). When I hit my fourth shot, he just came up and said, `Here's my card. I'm out of here.'"
About an hour after he left, McIlroy released a statement that pinned his withdrawal on dental problems.
"I have been suffering with a sore wisdom tooth, which is due to come out in the near future," McIlroy said. "It began bothering me again last night, so I relieved it with Advil. It was very painful again this morning, and I was simply unable to concentrate. It was really bothering me and had begun to affect my playing partners."
He was seen eating a sandwich on the 18th fairway.
McIlroy apologized to the tournament, saying he had every intention of defending his title at the Honda Classic. He said on Twitter he was "gutted."
"I'm a great fan of Rory's, but I don't think that was the right thing to do," Els said.
Told about McIlroy's statement about the sore wisdom tooth, Els softened his stance, not wanting to judge another player's pain.
"I didn't see anything, but if he had a toothache, that's what it is, you know?" Els said. "Hey, it's tough. If you ask him how he's feeling now, he's obviously feeling terrible for what's happened this morning."
"I didn't notice anything," Wilson said. "He wasn't playing the way the world No. 1 plays normally. Didn't hit the ball where he wanted to, and he's a true gentleman, though. He ... wasn't treating Ernie and myself in a different way. He was upset with his golf and I guess he had enough for the week."
McIlroy, coming off a year in which he won a second major in record fashion, already set himself up for scrutiny when he left Titleist to sign an equipment deal with Nike that was said to be worth upward of $20 million a year.
Nike introduced him with blaring music and a laser show in Abu Dhabi, but it's been all downhill from there.
McIlroy missed the cut in the Abu Dhabi Golf Championship with rounds of 75-75. He took a four-week break, and then was eliminated in the opening round of the Match Play Championship to Shane Lowry in one of the most poorly played matches of the round.
McIlroy played 36 holes with Tiger Woods at The Medalist on Sunday and said Tuesday it was no time to panic.
"Even though my results haven't revealed it, I really felt like I was rounding a corner," McIlroy said. "This is one of my favorite tournaments of the year and I regret having to make the decision to withdraw, but it was one I had to make."
It looked more like McIlroy was sinking than rounding the corner, not difficult to do on a course with so many water hazards. And he found plenty of them.
McIlroy, who opened with a 70, hit two poor chips that led to double bogey on No. 11, and a wild tee shot to the right led to a bogey on the 13th. His round really unraveled on the par-4 16th, when he hit his tee shot to the right and into the water, took a penalty drop and then came up short of the green and into the water again. He made a 6-foot putt for a triple bogey.
He three-putted from 40 feet, running his first putt about 10 feet by the hole, for a bogey to go 7 over. And then came the approach on the 18th that found water for the third time on his short day.
McIlroy is scheduled to play next week in the Cadillac Championship at Doral, which has no cut, and then the Houston Open. But on the first day of March, he has completed only four rounds of competition.
Els said the attention on McIlroy was sure to increase.
"I didn't think much of the equipment change. We've all made equipment changes before," said Els, who has used three brands of clubs to win majors. "I think there was a bit of criticism somewhere, and then I think he's furthering responding to that, and I think he's got a bit of pressure coming on him that way. I thought he played quite well yesterday. I thought he was pretty close to playing good golf, and unfortunately this morning ... hopefully he gets it together. We've got next week, got four rounds there. Such a talented player, he'll get it figured out."
It was the second straight year one of golf's biggest stars failed to finish a tournament on the Florida swing. Woods withdrew after 11 holes on the final round at Doral last year because of tightness in his Achilles tendon, raising questions about the seriousness of his recurring leg injuries. He won Bay Hill two weeks later.
McIlroy at least drove off from PGA National without a helicopter camera following him.