Rory McIlroy said he simply made "too many mistakes" in a topsy-turvy opening round of 73 at the Masters.
McIlroy looked set to finish the first day under par when he followed up back-to-back bogeys on the 10th and 11th with three birdies in four holes from the 13th.
However, the four-time major champion - who only needs a win at Augusta to complete a career Grand Slam - then dropped shots on 17 and 18 in a frustrating finish.
As he addressed reporters after his round, McIlroy was four off the lead and reflecting on what might have been.
"Yeah, just too many mistakes," he said. "I made six bogeys out there. I made enough birdies, I made five birdies, I just made too many mistakes ... and mistakes from very simple positions.
"It would have been great to shoot under par. It's not as if anyone is really getting away out there, but I could be starting tomorrow [Friday] a couple of shots better.
"Even though only three under is leading, I thought the course was there. It's soft, you can take advantage of those conditions and I just didn't do that."
Asked what he needed to do in round two, McIlroy immediately responded: "Putt better. I didn't putt well today.
"For the most part, my reads weren't good. I started off by over-reading a couple of putts and then under-reading. I just couldn't get my reads all day.
"I just have to get off to a good start tomorrow and try to get myself back into red figures."
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