Rory McIlroy's dream of becoming just the sixth man to win all four Grand Slam titles lay in tatters on Saturday despite the Northern Irishman carding a fine 69 in the third round of the Masters.

The world number one started the day a daunting 12 strokes behind leader Jordan Spieth and had a mountain to climb.

But he made a barnstorming start with an eagle at the second, thanks to a 37-footer, and birdies at eight and nine.

At that stage, he had clawed his way back to eight shots off the lead and two more birdies at 13 and 15 gave him a clear sight at Spieth.

But bogeys at the last two holes sent him in with a 69 and at six under he was facing an impossible task on Sunday to win his fifth major.

"Yeah, I got off to a good start. Sort of the way I wanted to play the front nine," he said.

"I had not really played the front nine too well the last couple days, so to play them under par is nice.

"Made a couple good birdies on 13 and 15. Felt like the other holes on the back nine were playing pretty tough with the pin positions and a bit of a swirling wind.

"So yeah, got it to 8-under-par through 15, and then a disappointing finish. But overall felt like I played pretty well."

McIlroy needs just a win in the Masters at some stage to match Grand Slammers Tiger Woods, Jack Nicklaus, Gary Player, Ben Hogan and Gene Sarazen.

He won the US Open in 2011, the PGA Championship in 2012 and 2014 and the British Open in 2014.

The career Grand Slam apart, a win on Sunday would make him only the third man to win three majors in a row and put him on the cusp of becoming just the second man after Woods to hold all four major titles at the same time.

At 25, he has time on his side, but needs to work out a way of playing four good rounds at Augusta National. His best so far in six previous appearances was a tie for eighth last year.

Asked what it was that was that was stopping him from playing his best at Augusta National, a course he feels is well suited to his game, McIlroy replied: "I don't know, silly mistakes.

"I missed a couple of short ones yesterday on greens.

"I definitely feel like I play this golf course better and better every year that I come here. I just need to keep putting numbers up like I did today. I know I'm capable of it.

"There are just a few stretches of holes that have held me back and that has really been the case this year again."
Source: AFP