First round Masters photo gallery
McILroy, at age 21, is attempting to become the youngest winner of the Masters since Tiger Woods in 1997. He took advantage of perfect conditions on day one to become the youngest first round leader in Master's history.
"I trusted everything," he said. "I trusted where I wanted to hit the ball. That's the key around here. With some of these pins, you can get tentative and try to guide it in there. You just have to pick your targets and trust your swing. I was very happy with the way I did that."
Quiros, the longest driver on tour, shot his lowest round at the Masters by 10 shots.
Trailing two shots behind at 5-under are 2009 PGA Champion Y.E. Yang, along with fellow Korean K.J. Choi.
Defending champion Phil Mickelson struggled with his driving accuracy all day, and finished with a 2-under 70.
Leaderboard
Photo: Rory McILroy / Getty Images
