Rory McIlroy believes it is "unthinkable" that he will not win the Masters at some point to complete the career grand slam.

And the world number one has revealed how his final-round collapse at Augusta National in 2011 was the most important day of his career.

McIlroy is looking to claim his first green jacket and become just the sixth player to win all four major titles after Gene Sarazen, Ben Hogan, Gary Player, Jack Nicklaus and Tiger Woods.

"For me now it's a career-long goal to win there to achieve something that only a handful of players have ever achieved," the 25-year-old said in an interview with BBC Northern Ireland.

"There's something special I can achieve going into Augusta this year. You are a complete player if you can win every major because they are on different golf courses, different tests, different conditions. Not many guys have done it in history so to put my name there would be awesome. It would just be incredible.

"The golf course was my sanctuary, it was where I could get away from everything." - Rory McIlroy

"You feel the sense of what can be achieved but I can't think about that too much. I just have to think about trying to go out there and playing as best as I can and if I can do that hopefully my scores add up to a shot lower than anyone else's."

McIlroy has just one top-10 finish to his name in six Masters appearances, finishing joint eighth last year despite the embarrassment of being outscored by his marker in the third round.

But the 25-year-old cannot picture going through his career without slipping on at least one coveted green jacket.

"During my career, yes it's unthinkable," he added. "If I don't win it this year...either it's not the right time or it isn't your time. If I was to look back as a 60-year-old on my career and not have won a green jacket I'd obviously be very, very disappointed.

"And not just one. I feel like it's a course I can do very well at and a golf course I can hopefully win multiple times on. Obviously getting that first one is extra important and from there we can go on and maybe think about getting some others."

McIlroy held a four-shot lead going into the final round four years ago, only to collapse to a closing 80 and finish 10 shots behind the winner Charl Schwartzel.

But he bounced back to win his first major title by eight shots in the US Open two months later, before adding wins in the 2012 US PGA and both the Open and US PGA last year.

"I think it was the most important day of my career," he added. "If I hadn't had the whole unravelling and say I just made a couple of bogeys coming down the stretch and lost by one, I might not have learnt as much.

"But for it all to come apart how it did I learnt an awful lot. I learnt so much about myself and my game and what I needed to do differently the next time I was in that position.

"Luckily it didn't take me long to get into a position like that again where I was leading a major and we know how that one played out. I was able to get over the line pretty comfortably."

McIlroy's extraordinary success last year came despite the distractions of calling off his wedding to Caroline Wozniacki and a legal dispute with his former management company, which cost him millions of pounds when it was finally settled in February.

And he hopes he can again use the golf course as his "sanctuary" from the pressure and hype surrounding Augusta.

"The golf course was my sanctuary, it was where I could get away from everything and just not have to think about it for the four or five hours that I am out there and it helped. It really did," he added.

"I was looking forward to getting to the course and playing and practising and I think it will be the same at Augusta because there will be so much hype and build up and talk about what could happen.

"I know I won't be able to wait until Thursday morning or afternoon and just get on the golf course and play golf. There is only so much you can talk about it and then you have to go out and try and play."