McIlroy made three successive bogeys early en route to a four-over-par 76, his worst first-round score in 13 appearances at the tournament, one shot more than his disappointing effort at last November's Masters.

Eleven years after nearly winning a green jacket as a precocious 20-year-old, the Northern Irishman seems further than ever from capturing the one title he still needs to complete the career grand slam of all four majors.

No wonder he looked weary and downbeat as he walked off the course, struggling even to chuckle much as he recounted his approach shot at the 7th hole that struck his father Gerry on the back of the leg.

McIlroy has been tweaking his swing recently with new instructor Pete Cowen.

"I hit some loose shots out there ... It was just one of those days where I wasn't very efficient with my scoring." – Rory McIlroy

He acknowledges it is a work in progress and, while he observed his solid play over the closing holes as cause for optimism, he was speaking before Ryder Cup teammate Rose disappeared almost out of sight with a sizzling back nine.

"I hit some loose shots out there, but after hitting the 6-iron in the water on 13, I hit some really good shots coming in, so I'm encouraged by that," McIlroy said.

"(I will be) going to go to the range here and work on it a little bit more, but it was just one of those days where I wasn't very efficient with my scoring."

McIlroy said he felt uncomfortable with his swing from uneven lies, of which there are plenty at hilly Augusta National.

"On the range off a flat lie, yeah, perfect, I can do it every time, but then once you get on the golf course and you get these different lies and different shots and different winds, that's the litmus test right there.

"And it still didn't feel quite 100 percent."

The two players who overturned seven-shot first-round deficits to win the Masters were Tiger Woods in 2005 and Nick Faldo in 1990.