Rory McIlroy vowed to cut out the careless mistakes after beginning his Masters campaign with an erratic level-par 72 at Augusta National.
The world No 2 appeared poised to challenge for the lead when he covered the front nine in 34 blows with three birdies and one bogey at the seventh.
But he frittered shots away at the 10th and 12th, and although he birdied the two par-fives, he also bogeyed 14 and 17 to slip six shots behind the leaders.
"It could have been better," McIlroy said. "I felt like I played well and gave myself plenty of opportunities.
"I just made some silly mistakes, a couple of three-putts on the back nine. I made enough birdies but I just need to cut those mistakes out and I'll be fine.
"I turned in two-under par and everything felt good. That was the story of the day any time I got a bit of momentum I gave it straight back.
"Around this course you really can't do that. I feel like the game is there, I mean I hit the ball really well.
"As long as I keep giving myself birdie opportunities like that and take a few of them, hopefully I can go out and post a good one on Friday.
"I am getting there. I think I am hitting the ball just as well. It is just a matter of taking the opportunities and limiting the mistakes."